Continuous Carbon Sequestration Material Production Methods and Systems for Practicing the Same

ABSTRACT

Methods of producing solid CO 2  sequestering carbonate materials are provided. Aspects of the methods include introducing a divalent cation source into a flowing aqueous liquid (e.g., a bicarbonate rich product containing liquid) under conditions sufficient such that a non-slurry solid phase CO 2  sequestering carbonate material is produced. Also provided are systems configured for carrying out the methods.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(e), this application claims priority to thefiling dates of U.S. Provisional Application Ser. No. 62/062,084 filedon Oct. 9, 2014; U.S. Provisional Application Ser. No. 62/163,107 filedon May 18, 2015; U.S. Provisional Application Ser. No. 62/163,118 filedon May 18, 2015; and U.S. Provisional Application Ser. No. 62/200,542filed on Aug. 3, 2015; the disclosures of which applications are hereinincorporated by reference.

INTRODUCTION

Carbon dioxide (CO₂) is a naturally occurring chemical compound that ispresent in Earth's atmosphere as a gas. Sources of atmospheric CO₂ arevaried, and include humans and other living organisms that produce CO₂in the process of respiration, as well as other naturally occurringsources, such as volcanoes, hot springs, and geysers.

Additional major sources of atmospheric CO₂ include industrial plants.Many types of industrial plants (including cement plants, refineries,steel mills and power plants) combust various carbon-based fuels, suchas fossil fuels and syngases. Fossil fuels that are employed includecoal, natural gas, oil, petroleum coke and biofuels. Fuels are alsoderived from tar sands, oil shale, coal liquids, and coal gasificationand biofuels that are made via syngas.

The environmental effects of CO₂ are of significant interest. CO₂ iscommonly viewed as a greenhouse gas. Because human activities since theindustrial revolution have rapidly increased concentrations ofatmospheric CO₂, anthropogenic CO₂ has been implicated in global warmingand climate change, as well as increasing oceanic bicarbonateconcentration. Ocean uptake of fossil fuel CO₂ is now proceeding atabout 1 million metric tons of CO₂ per hour.

Concerns over anthropogenic climate change and ocean acidification,compounded with recent changes in U.S. Federal policy to include carbondioxide (CO₂) as a regulated air pollutant, have fueled an urgency todiscover scalable and cost effective methods of carbon capture andsequestration (CCS).

SUMMARY

Methods of producing solid CO₂ sequestering carbonate materials areprovided. Aspects of the methods include introducing a divalent cationsource into a flowing aqueous liquid (e.g., a bicarbonate rich productcontaining liquid) under conditions sufficient such that a non-slurrysolid phase CO₂ sequestering carbonate material is produced. Alsoprovided are systems configured for carrying out the methods.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 provides a depiction of a fluidized bed reactor in accordancewith an embodiment of the invention.

FIG. 2 provides a schematic representation of a specific embodiment of amethod in accordance with an embodiment of the invention.

FIG. 3: Laminar Flow Continuous Reactor; counter clockwise flow, 10′ ABSpolymer, 3″ diameter. Flow rates 153 ml/sec alkaline flow, 100 ml/mindivalence flow. 36 second residence time.

FIG. 4: SEM images showing ability to form materials from 30 μ (upperleft & right), 100 μ (lower left), and over 200 μ (lower left).

FIG. 5: Particle size distribution of precipitated powder.

FIG. 6: Ooid materials tested in mortar.

FIG. 7: SEM (left) precipitate, (right) hard scale.

FIG. 8: Continuous Beaker Reactor employed in the Experimental Section,below.

FIG. 9: Scaled carbonate on heating element

FIG. 10: Scale formed in alkaline delivery tube (occluding tube)

FIG. 11: Scale on templating carbonates—limestone (left image), C11 (BPcarbonate cement sample (middle), S217&S245 (right image)

FIG. 12: Percolation Pressure Drop (dP) Continuous System employed inthe Experimental Section, below.

FIG. 13: Common Images of various template and non-templated liquifiedmaterials produced by percolation pressure drop.

FIG. 14: Fluid bed reactor employed in the Experimental Section, below.

FIG. 15: SEM of accreted templating materials, cross section and varioustemplates

FIG. 16: Solar Reflectance of accreted materials

FIG. 17: Compressive strength data of accreted materials in ASTM C109mortar testing.

FIG. 18A provides a picture of a fine aggregate material prior tocarbonate coating in accordance with an embodiment of the invention,FIG. 18B provides a picture of the fine aggregate of FIG. 18A aftercarbonate coating in accordance with an embodiment of the invention.

FIG. 19A provides a picture of a pumice prior to coating, while FIG. 19Bprovides a picture of the pumice after coating.

FIG. 20 provides photographs of fine comprising pumice and limestoneaggregate precursor compositions (left hand side) before and aftercontact with an acidic solution, as described in greater detail below inthe experimental section.

FIG. 21: Trough Continuous System employed in the Experimental Section,below.

DETAILED DESCRIPTION

Methods of producing solid CO₂ sequestering carbonate materials areprovided, Aspects of the methods include introducing a divalent cationsource into a flowing liquid (e.g., a bicarbonate rich productcontaining liquid) under conditions sufficient such that a non-slurrysolid phase CO₂ sequestering carbonate material is produced. Alsoprovided are systems configured for carrying out the methods.

Before the present invention is described in greater detail, it is to beunderstood that this invention is not limited to particular embodimentsdescribed, as such may, of course, vary. It is also to be understoodthat the terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting, sincethe scope of the present invention will be limited only by the appendedclaims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges and are also encompassed within the invention, subject toany specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the invention.

Certain ranges are presented herein with numerical values being precededby the term “about.” The term “about” is used herein to provide literalsupport for the exact number that it precedes, as well as a number thatis near to or approximately the number that the term precedes. Indetermining whether a number is near to or approximately a specificallyrecited number, the near or approximating un-recited number may be anumber which, in the context in which it is presented, provides thesubstantial equivalent of the specifically recited number.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present invention, representativeillustrative methods and materials are now described.

All publications and patents cited in this specification are hereinincorporated by reference as if each individual publication or patentwere specifically and individually indicated to be incorporated byreference and are incorporated herein by reference to disclose anddescribe the methods and/or materials in connection with which thepublications are cited. The citation of any publication is for itsdisclosure prior to the filing date and should not be construed as anadmission that the present invention is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dateswhich may need to be independently confirmed.

It is noted that, as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. It is further noted that the claimsmay be drafted to exclude any optional element. As such, this statementis intended to serve as antecedent basis for use of such exclusiveterminology as “solely,” “only” and the like in connection with therecitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinvention. Any recited method can be carried out in the order of eventsrecited or in any other order which is logically possible.

Methods

As summarized above, aspects of the invention include methods ofproducing a CO₂ sequestering carbonate material. By CO₂ sequesteringcarbonate material is meant a material that stores a significant amountof CO₂ in a storage-stable format, such that CO₂ gas is not readilyproduced from the material and released into the atmosphere. In certainembodiments, the CO₂-sequestering material includes 5% or more, such as10% or more, including 25% or more, for instance 50% or more, such as75% or more, including 90% or more of CO₂, e.g., present as one or morecarbonate compounds. The CO₂-sequestering materials produced inaccordance with methods of the invention may include one or morecarbonate compounds, e.g., as described in greater detail below. Theamount of carbonate in the CO₂-sequestering material, e.g., asdetermined by coulometry, may be 40% or higher, such as 70% or higher,including 80% or higher.

CO₂ sequestering materials, e.g., as described herein, provide forlong-term storage of CO₂ in a manner such that CO₂ is sequestered (i.e.,fixed) in the material, where the sequestered CO₂ does not become partof the atmosphere. When the material is maintained under conditionsconventional for its intended use, the material keeps sequestered CO₂fixed for extended periods of time (e.g., 1 year or longer, 5 years orlonger, 10 years or longer, 25 years or longer, 50 years or longer, 100years or longer, 250 years or longer, 1000 years or longer, 10,000 yearsor longer, 1,000,000 years or longer, or even 100,000,000 years orlonger) without significant, if any, release of the CO₂ from thematerial. Wth respect to the CO₂-sequestering materials, when they areemployed in a manner consistent with their intended use and over theirlifetime, the amount of degradation, if any, as measured in terms of CO₂gas release from the product will not exceed 10% per year, such as 5%per year, and in certain embodiments, 1% per year. In some instances,CO₂-sequestering materials provided by the invention do not release morethan 1%, 5%, or 10% of their total CO₂ when exposed to normal conditionsof temperature and moisture, including rainfall of normal pH, for thereintended use, for at least 1, 2, 5, 10, or 20 years, or for more than 20years, for example, for more than 100 years. Any suitable surrogatemarker or test that is reasonably able to predict such stability may beused. For example, an accelerated test comprising conditions of elevatedtemperature and/or moderate to more extreme pH conditions is reasonablyable to indicate stability over extended periods of time. For example,depending on the intended use and environment of the composition, asample of the composition may be exposed to 50, 75, 90, 100, 120, or150° C. for 1, 2, 5, 25, 50, 100, 200, or 500 days at between 10% and50% relative humidity, and a loss less than 1%, 2%, 3%, 4%, 5%, 10%,20%, 30%, or 50% of its carbon may be considered sufficient evidence ofstability of materials of the invention for a given period (e.g., 1, 10,100, 1000, or more than 1000 years).

Aspects of the invention include continuous processes to produce solidCO₂ sequestering carbonate materials. As the processes are continuous,they are not batch processes. In practicing continuous processes of theinvention, a divalent cation source is introduced into a flowing aqueousliquid (e.g., a bicarbonate rich product containing liquid) underconditions sufficient such that a non-slurry solid phase CO₂sequestering carbonate material is produced in the flowing aqueousbicarbonate rich product.

Divalent Cation Source

In practicing methods of the invention, any convenient divalent cationsource may be employed. Divalent cations, such as alkaline earth metalcations, e.g., calcium and magnesium cations, are of interest. Cationsources of interest include, but are not limited to, the brine fromwater processing facilities, such as sea water desalination plants,brackish water desalination plants, groundwater recovery facilities,wastewater facilities, and the like, which produce a concentrated streamof solution high in cation contents. Also of interest as cation sourcesare naturally occurring sources, such as, but not limited to, nativeseawater and geological brines, which may have varying cationconcentrations and may also provide a ready source of cations to triggerthe production of carbonate solids from a bicarbonate rich product orcomponent thereof (e.g., LCP), such as described in greater detailbelow. The cation source employed in such solid carbonate productionsteps may be the same as or different from the aqueous media employed inthe bicarbonate rich product production step, e.g., as described below.In some instances, the cation source may be one that has been producedusing a membrane mediated protocol, e.g., as described in PCTApplication Serial No. US2015/018361 now published as WO 2015/134408;the disclosure of which is herein incorporated by reference.

A given divalent cation source may be a solid or liquid, as desired. Forexample, a liquid divalent cation source may be employed. Alternatively,a solid divalent cation source, such as a particulate source (e.g., apowder) may be employed.

Aqueous Flowing Liquid

As summarized above, in practicing methods of the invention the divalentcation source is introduced into an aqueous flowing liquid. Aqueousflowing liquids in which a divalent cation source may be introducedinclude bicarbonate and/or carbonate containing liquids. Where theliquid is a bicarbonate and/or carbonate containing liquid, it is liquidthat includes bicarbonate ions and/or carbonate ions. The pH of theliquid may vary, ranging in some instances from 7 to 14, such as 7 to12.

In some instances, the liquid is a bicarbonate rich product containingliquid. Bicarbonate rich product containing liquids that find usemethods of the invention include, but are not limited to, two-phaseliquids that include droplets of a liquid condensed phase (LCP) in abulk liquid, e.g., bulk solution. By “liquid condensed phase” or “LCP”is meant a phase of a liquid solution which includes bicarbonate ions,wherein the concentration of bicarbonate ions is higher in the LCP phasethan in the surrounding, bulk liquid.

LCP droplets are characterized by the presence of a meta-stablebicarbonate-rich liquid precursor phase in which bicarbonate ionsassociate into condensed concentrations exceeding that of the bulksolution and are present in a non-crystalline solution state. The LCPcontains all of the components found in the bulk solution that isoutside of the interface. However, the concentration of the bicarbonateions is higher than in the bulk solution. In those situations where LCPdroplets are present, the LCP and bulk solution may each containion-pairs and pre-nucleation clusters (PNCs). When present, the ionsremain in their respective phases for long periods of time, as comparedto ion-pairs and PNCs in solution.

The bulk phase and LCP are characterized by having different K_(eq),different viscosities, and different solubilities between phases.Bicarbonate, carbonate, and divalent ion constituents of the LCPdroplets are those that, under appropriate conditions, may aggregateinto a post-critical nucleus, leading to nucleation of a solid phase andcontinued growth. While the association of bicarbonate ions withdivalent cations, e.g., Ca²⁺, in the LCP droplets may vary, in someinstances bidentate bicarbonate ion/divalent cation species may bepresent. For example, in LCPs of interest, Ca²⁺/bicarbonate ionbidentate species may be present. While the diameter of the LCP dropletsin the bulk phase of the LCP may vary, in some instances the dropletshave a diameter ranging from 1 to 500 nm, such as 10 to 100 nm. In theLCP, the bicarbonate to carbonate ion ratio, (i.e., the HCO₃ ³¹ /CO_(d)²⁻ ratio) may vary, and in some instances is 10 or greater to 1, such as20 or greater to 1, including 25 or greater to 1, e.g., 50 or greaterto 1. Additional aspects of LCPs of interest are found in Bewernitz etal., “A metastable liquid precursor phase of calcium carbonate and itsinteractions with polyaspartate,” Faraday Discussions, 7 Jun. 2012. DOI:10.1039/c2fd20080e (2012) 159: 291-312. The presence of LCPs may bedetermined using any convenient protocol, e.g., the protocols describedin Faatz et al., Advanced Material, 2004, 16, 996-1000; Wolf et al.,Nanoscale, 2011, 3, 1158-1165; Rieger et al., Faraday Discussions, 2007,136, 265-277; and Bewernitz et al., Faraday Discussions, 2012, 159,291-312.

Where the bicarbonate rich product liquid has two phases, e.g., asdescribed above, the first phase may have a higher concentration ofbicarbonate ion than a second phase, where the magnitude of thedifference in bicarbonate ion concentration may vary, ranging in someinstances from 0.1 to 4, such as 1 to 2. For example, in someembodiments, a bicarbonate rich product liquid may include a first phasein which the bicarbonate ion concentration ranges from 1000 ppm to 5000ppm, and a second phase where the bicarbonate ion concentration ishigher, e.g., where the concentration ranges from 5000 ppm to 6000 ppmor greater, e.g., 7000 ppm or greater, 8000 ppm or greater, 9000 ppm orgreater, 10,000 ppm or greater, 25,000 ppm or greater, 50,000 ppm orgreater_(;) 75,000 ppm or greater, 100,000 ppm, 500,000 or greater.

In addition to the above characteristics, a given bicarbonate richproduct liquid may include a number of additional markers which serve toidentify the source of CO₂ from it has been produced. For example, agiven bicarbonate component may include markers which identify the waterfrom which it has been produced. Waters of interest include naturallyoccurring waters, e.g., waters obtained from seas, oceans, lakes,swamps, estuaries, lagoons, brines, alkaline lakes, inland seas, as wellas man-made waters, e.g., brines produced by water desalination plants,and the like. In such instances, markers that may be present includeamounts of one or more of the following elements: Ca, Mg, Be, Ba, Sr,Pb, Fe, Hg, Na, K, Li, Mn, Ni, Cu, Zn, Cu, Ce, La, Al, Y, Nd, Zr, Gd,Dy, Ti, Th, U, La, Sm, Pr, Co, Cr, Te, Bi, Ge, Ta, As, Nb, W, Mo, V,etc. Alternatively or in addition to the above markers, a givenbicarbonate component may include markers which identify the particularCO₂-containing gas used to produce the bicarbonate component. Suchmarkers may include, but are not limited to, one or more of: nitrogen,mononitrogen oxides, e.g., NO, NO₂ and NO₃, oxygen, sulfur, monosulfuroxides, e.g., SO, SO₂ and SO₃), volatile organic compounds, e.g.,benzo(a)pyrene C₂OH₁₂, benzo(g,h,l)perylene C₂₂H₁₂,dibenzo(a,h)anthracene C₂₂H₁₄ etc. Particulate components that may bepresent in the CO₂ containing gas from which the bicarbonate componentis produced and therefore which may be present in the bicarbonatecomponent include, but are not limited to particles of solids or liquidssuspended in the gas, e.g., heavy metals such as strontium, barium,mercury, thallium, etc. When present, such markers may vary in theiramounts, ranging in some instances from 0.1 to 10,000, such as 1 to5,000 ppm.

Of interest in certain embodiments are agents (referred to herein as“bicarbonate promoters” or “BLCP promoters”) that promote the productionof high-bicarbonate-content bicarbonate additive (which may also bereferred to herein as a bicarbonate admixture), e.g., by promoting theproduction and/or stabilization of BLCPs, e.g., facilitating theformation of a BLCP in a bicarbonate-containing solution whilepreventing precipitation of the solution's components to form solidcarbonate-containing materials. A high-bicarbonate-content bicarbonatecomponent is one that has a bicarbonate content of 0.1 wt. % or greater,such as 4 wt. % or greater, including 10 wt. % or greater, such as abicarbonate component having a bicarbonate content ranging from 5 to 40wt. % such as 10 to 20 wt. %. The amount of bicarbonate promoter presentin a given bicarbonate component may vary, where in some instances theamount ranges from 0.000001 wt. % to 40 wt. %, such as 0.0001 to 20 wt.% and including 0.001 to 10 wt. %. Such promoters are further describedin U.S. patent application Ser. No. 14/112,495; the disclosure of whichis herein incorporated by reference.

In some instances, the liquid is a carbonate ion containing liquid.Carbonate ion containing liquids include aqueous media having a pH of 10or more, such as 11 or more, including 12 or more. Examples of suchliquid include, but are not limited to, those described in U.S. Pat.Nos. 8,333,944; 8,177,909; 8,137,455; 8,114,214; 8,062,418; 8,006,446;7,939,336; 7,931,809; 7,922,809; 7,914,685; 7,906,028; 7,887,694;7,829,053; 7,815,880; 7,771,684; 7,753,618; 7,749,476; 7,744,761; and7,735,274; the disclosures of which are herein incorporated byreference.

Introduction of Divalent Cations into a Flowing Aqueous Liquid

In practicing embodiments of the methods, divalent cations, e.g., asdescribed above, are introduced into a flowing liquid (such as abicarbonate rich product containing liquid, e.g., as described above),under conditions sufficient such that a non-slurry solid phase CO₂sequestering carbonate material is produced in the flowing aqueousliquid. By “flowing” aqueous liquid is meant a liquid (such as describedabove) that is moving, e.g., as a stream, such that it is notstationary. The flow rate of the liquid, e.g., as determined relative tothe site or location at which the divalent cations are introduced intothe liquid, may vary. In some instances, the flow rate of the liquidranges from 0.1 to 10 m/second, such as 0.2 to 2.0 m/s. In someinstances, the flow rate of the liquid ranges from 10 LPD to 40B LPD(liters per day), such as 400,000 LPD to 12M LPD.

In some instances, the liquid is flowing through a housing orcontainment structure, where the length of the flow path of the liquidmay vary. In some instances, the flow path ranges in length from 0.10 mto 100 m, such as 1 m to 10 m and including 1 m to 5.0 m. Along a givenflow path, the flow rate of the liquid may be constant or varied, asdesired. For example, the flow rate may be faster at the site ofdivalent cation introduction relative to the site of CO₂ sequesteringcarbonate material production. The magnitude of any change in flow ratemay vary, where the magnitude of such change, if present, ranges in someinstances from 2 to 100 times, such as 5 to 20 times. The flow rate maybe varied using any convenient protocol, e.g., by placing barriers inthe flow path, adjusting the elevation of the flow path, etc.

The amount of divalent cation source that is introduced into the liquidis sufficient to provide for the desired solid phase CO₂ sequesteringcarbonate material. While the amount may vary, in some instances theamount that is introduced into the liquid is sufficient to provide aconcentration of divalent cation in the liquid at a location in the flowpath just before material production that ranges from 10 ppm to 10,000ppm, such as 200 ppm to 2,000 ppm, Where the divalent cation source is aliquid source having a divalent cation concentration ranging from 500ppm to 20,000 ppm, such as 1000 ppm to 5000 ppm, the liquid divalentcation source may be introduced into the flowing liquid at a rateranging from 0.1 m/s to 10 mis, such as 0.2 mis to 4 m/s. Alternatively,where the divalent cation source is a dry powder having a divalentcation concentration of 10 to 80% wt/wt., the power divalent cationsource may be introduced into the flowing liquid at a rate ranging from0.2 m/s to 10 m/s, such as 0.2 m/s to 4 m/s.

As the process is a continuous process, upon initiation of the processno solid carbonate material product, apart from any seed structure(e.g., as described below), will be present in the production zone ofthe flow path before introduction of the divalent cations into theflowing liquid. In some embodiments, at a time following the initialintroduction of the divalent cations, a precursor composition forms atlocation downstream from the divalent cation introduction site. Whilethe time between initial introduction and the formation of the non-solidprecursor structure may vary, in some instances the time ranges from0.001 sec to 10 min, such as 0.1 sec to 1 min. In these embodiments, theprecursor composition forms at a distance from the divalent cationintroduction site, where the location may be downstream from thedivalent cation introduction site by a varying distance, where thisdistance may range in some instances from 1 cm to 10 m, such as 2 cm to2 m. The precursor composition may be characterized as a transient zonewhere the initial clusters of carbonate mineral have not yet formed apolytype of the carbonate mineral and are highly unstable, making themmore likely to accrete on to a solid surface than to homogeneouslycrystallize in solution to become part of a slurry.

The zone of accretion (carbonate growth) is defined by saturation indexwhere

SI=log (IAP/Ksp)

(IAP is the ion activity product over Ksp solubility product) inrelation to the activation energy (Stumm & Morgan 1981) where:

ΔG=16 πσ{circumflex over ( )}3 v{circumflex over ( )}2/[3(kT LnS){circumflex over ( )}2

where σ is the interfacial energy, v is the molecular volume, k isBoltzmann's constant, T is the absolute temperature, Ln is the naturallogarithm operator, S is the relative supersaturation.

The zone of accretion can furthermore be modified by pressure,temperature and flow rate. Supersaturated solutions between 1× and 1000×supersaturation are of interest, such as 10× and 500× super saturationand including 11× and 300× supersaturation. The zone of accretion may beof a transient nature such that periodic dosing of various divalentcations results in periodicity of saturation index flows through thesystem. Also periodic alkaline component solutions can be introduced tobrine solutions or solutions containing divalent cations creatingsimilar response. Periodicity similar to diurnal cyclic variance seen ingeologic settings where beach rock forms (Ref. Sedimentary Geology, 33(1982) 157-172.

The system may be catalyzed by pH modification in the acidic or basicdirection or using any convenient protocol. Introduction of CO₂ orcarbonic acid into the reactor vessel isone modality of acidifying thesystem and modifying the zone of accretion. Another modality is theintroduction of acid, e.g., hydrochloric acid (HCl). In such instances,HCl concentrations between 0.01 and 20%, such as between 0.5 and 10%,including between 1 and 3% may be employed. In some instances, anelectrochemical protocol may be employed to increase the pH of thebicarbonate liquid to produce the concentrated bicarbonate liquid.Electrochemical protocols may vary, and in some instances include thoseemploying an ion exchange membrane and electrodes, e.g., as described inU.S. Pat. Nos. 8,357,270; 7,993,511; 7,875,163; and 7,790,012; thedisclosures of which are herein incorporated by reference. Alkalinitymodulation, e.g., increase or decrease, of the bicarbonate containingliquid may also be accomplished by adding a suitable amount of achemical agent to the bicarbonate containing liquid. Chemical agents foreffecting proton removal generally refer to synthetic chemical agentsthat are produced in large quantities and are commercially available.For example, chemical agents for removing protons include, but are notlimited to, hydroxides, organic bases, super bases, oxides, ammonia, andcarbonates. Hydroxides include chemical species that provide hydroxideanions in solution, including, for example, sodium hydroxide (NaOH),potassium hydroxide (KOH), calcium hydroxide (Ca(OH)₂), or magnesiumhydroxide (Mg(OH)₂). Organic bases are carbon-containing molecules thatare generally nitrogenous bases including primary amines such as methylamine, secondary amines such as diisopropylamine, tertiary such asdiisopropylethylamine, aromatic amines such as aniline, heteroaromaticssuch as pyridine, imidazole, and benzimidazole, and various formsthereof. In some embodiments, an organic base selected from pyridine,methylamine, imidazole, benzimidazole, histidine, and a phophazene isused to remove protons from various species (e.g., carbonic acid,bicarbonate, hydronium, etc.) for precipitation of precipitationmaterial. In some embodiments, ammonia is used to raise pH to a levelsufficient to precipitate precipitation material from a solution ofdivalent cations and an industrial waste stream. Super bases suitablefor use as proton-removing agents include sodium ethoxide, sodium amide(NaNH₂), sodium hydride (NaH), butyl lithium, lithium diisopropylamide,lithium diethylamide, and lithium bis(trimethylsilyl)amide. Oxidesincluding, for example, calcium oxide (CaO), magnesium oxide (MgO),strontium oxide (SrO), beryllium oxide (BeO), and barium oxide (BaO) arealso suitable proton-removing agents that may be used.

Various condition parameters may be modulated during a given method toachieve a desired production of CO₂ sequestering carbonate material. Forexample, pressure may be maintained at a constant level along the flowpath, or pressure may be modulated (i.e., varied) along the flow path,as desired. While the pressure may vary in a given method, in someinstances the pressure ranges from 0.1 atm to 100 atm, such as 1 atm to10 atm. In some embodiments, the pressure is varied, e.g., decreased,along the flow path. The magnitude of any change in pressure may vary,where the magnitude of such change, if present, ranges in some instancesfrom 2 to 100 times, such as 5 to 10 times. The pressure may be variedusing any convenient protocol, e.g., by reducing or increasing thevolume of the flow path at a given location, fluid regime, etc. In someinstances, the pressure is reduced at the location of CO₂ sequesteringcarbonate material relative to the divalent cation introduction site,e,g., where the magnitude of reduction may range from 0% to 100 or more%, such as 10% to 100%.

Alternatively or in addition, the temperature may be maintained at aconstant level along the flow path, or modulated (i.e., varied) alongthe flow path, as desired, While the temperature may vary in a givenmethod, in some instances the temperature ranges from −4° C. to +99° C.,such as 0° C. to 80° C. In some embodiments, the temperature is varied,e.g., decreased or increased, along the flow path. The magnitude of anychange in temperature may vary, where the magnitude of such change, ifpresent, ranges in some instances from 1 to 50° C., such as 2 to 25° C.The temperature may be varied using any convenient protocol, e.g., byheating or cooling the liquid at various location(s) of the flow path.

In some instances, the solid phase CO₂ sequestering carbonate materialis produced at a location that is downstream from the divalent cationsource introduction site. By downstream is meant a location along theflow path in the direction of fluid flow that is separated from thedivalent cation introduction site. The distance between the divalentcation introduction site and the material production site may vary,ranging in some instances from 1 cm to 2.5 km, such as 5 cm to 100 m.

Introduction of the divalent cation source into the flowing liquid,e,g., as described above, results in the production of a non-slurrysolid phase CO₂ sequestering carbonate material. By non-slurry solidphase is meant a solid phase that is not a slurry, i.e., if maintainedunder static conditions it would not be a suspension of small particlesin a liquid. As such, upon cessation of flowing liquid through thematerial production zone, the solid phase material produced according toembodiments of the methods settles (i.e., falls) out of suspension in 10min or less, such as 5 min or less, and in some instances 1 min or less.As the material is a non-slurry solid phase, in some instances thelongest dimension of a given amount of the produced material is 30 μm orgreater, such as 100 μm or greater, including 1000 μm or greater. Insome instances the product material is a particulate composition that ismade up of a plurality of distinct particles. In such instances, theplurality of distinct particles may vary in size, ranging in someinstances from 10 to 1,000,000 μm, such as 1,000 to 100,000 μm andincluding 5,000 to 50,000 μm. In such compositions, the mean diameter ofthe particles may vary, and in some instances ranges from 20 to 20,000μm, such as 200 to 8,000 μm. The particles of such compositions may beregular or irregular, where in some instances the particles are ooids.In these embodiments, the carbonate material may be produced bysuccessive coating of carbonate compounds onto growing particles,resulting in production of particulates as described above. In someinstances, the non-slurry solid phase CO₂ sequestering carbonatematerial is a liquified unitary object. While the dimensions of such anobject may vary, in some instances the object has a longest dimensionranging from 1,000 to 100,000, such as 5,000 to 50,000 μm. In theseinstances, the liquified object(s) produced in the production zone maybe produced by carbonate materials forming in pores or interstices ofpre-existing structures, uniting and agglomerating such structures intoliquified masses.

The product carbonate materials may vary greatly. The product mayinclude one or more different carbonate compounds, such as two or moredifferent carbonate compounds, e.g., three or more different carbonatecompounds, five or more different carbonate compounds, etc., includingnon-distinct, amorphous carbonate compounds. Carbonate compounds ofproducts of the invention may be compounds having a molecularformulation X_(m)(CO₃)_(n) where X is any element or combination ofelements that can chemically bond with a carbonate group or itsmultiple, wherein X is in certain embodiments an alkaline earth metaland not an alkali metal; wherein m and n are stoichiometric positiveintegers. These carbonate compounds may have a molecular formula ofX_(m)(CO₃)_(n).H₂O, where there are one or more structural waters in themolecular formula. The amount of carbonate in the product, as determinedby coulometry using the protocol described as coulometric titration, maybe 40% or higher, such as 70% or higher, including 80% or higher.

In some instances solid solutions of phosphate, sulfate, borate, andsilicate minerals and the like may develop with the carbonate, whereinthe carbonate is still the dominant anionic complex. These other anions,when present, may substitute into the crystal lattice for the carbonateion and occur, in some instances, below 50%, such as below 20%, and insome instances below 10%, to even just a few to less than 1%.

The carbonate compounds of the products may include a number ofdifferent cations, such as but not limited to ionic species of: calcium,magnesium, sodium, potassium, sulfur, boron, silicon, strontium, andcombinations thereof. Of interest are carbonate compounds of divalentmetal cations, such as calcium and magnesium carbonate compounds.Specific carbonate compounds of interest include, but are not limitedto: calcium carbonate minerals, magnesium carbonate minerals and calciummagnesium carbonate minerals. Calcium carbonate minerals of interestinclude, but are not limited to: calcite (CaCO₃), aragonite (CaCO₃),vaterite (CaCO₃), ikaite (CaCO₃.H₂O), and amorphous calcium carbonate(CaCO₃). Magnesium carbonate minerals of interest include, but are notlimited to magnesite (MgCO₃), barringtonite (MgCO₃.2H₂O), nesquehonite(MgCO₃.3H₂O), lanfordite (MgCO₃.5H₂O), hydromagnisite, and amorphousmagnesium calcium carbonate (MgCO₃). Calcium magnesium carbonateminerals of interest include, but are not limited to dolomite(CaMg)(CO₃)₂), huntite (Mg₃Ca(CO₃)₄) and sergeevite(Ca₂Mg₁₁(CO₃)₁₃.H₂O). The carbonate compounds of the product may includeone or more waters of hydration, or may be anhydrous. In some instances,the amount by weight of magnesium carbonate compounds in the precipitateexceeds the amount by weight of calcium carbonate compounds in theprecipitate. For example, the amount by weight of magnesium carbonatecompounds in the precipitate may exceed the amount by weight calciumcarbonate compounds in the precipitate by 5% or more, such as 10% ormore, 15% or more, 20% or more, 25% or more, 30% or more. In someinstances, the weight ratio of magnesium carbonate compounds to calciumcarbonate compounds in the precipitate ranges from 1.5-5 to 1, such as2-4 to 1 including 2-3 to 1. In some instances, the product may includehydroxides, such as divalent metal ion hydroxides, e.g., calcium and/ormagnesium hydroxides.

In some instances, the product that is produced is a white, highlyreflective carbonate material, i.e., the material appears white in colorto the human eye. As the material appears white to the human eye, it maybe true white or light gray in actual color or hue. In some instances,the white material reflects 60% or more of incident light, such as 70%or more of incident, e.g., 80% or more, 90% or more, 95% or more, 99% ormore, including, in some instances, 100% of incident light e.g., asmeasured by ASTM C1549. The product material may, in some instances, bea white pigment composition, e.g., as described in PCT PatentApplication Serial No. US2015/047408 filed on Aug. 29, 2014; thedisclosure of which is herein incorporated by reference.

In yet other embodiments, the product materials are carbonate coolpigment compositions. As the materials of these embodiments are coolpigment compositions, they have a low infrared absorptioncharacteristic, i.e., they are highly reflective of infrared light,e.g., as compared to non-carbonate materials having the substantiallythe same, if not the same, color. For example, the NIR reflectance valueof a brown cool pigment of the present invention is, in some instances,10% or greater, such as 25% greater, including 50% or greater, ascompared to the NIR reflectance value of a reference or control brownpigment of the same hue which is does not include a transition metalcarbonate, e.g., as described herein. The cool pigment materialsdescribed herein are reflective of near infra-red (NIR) light. By NIRlight is meant light having a wavelength ranging from 700 nanometers(nm) to 2.5mm. The carbonate cool pigment materials described herein arecolored. By “colored” is meant that they are non-white. As such, they donot appear white in color to the human eye. The color of a givencarbonate cool pigment composition as described herein may becharacterized by the CIELAB color system. As used in the presentspecification and claims, L*, a* and b* refer to the parameters of theCIELAB color system. As used in the present specification and claims,“colored” means having an L* value of 95 or less, such as 90 or less,including 85 or less. In some instances, the pigments have an L* valueranging from 10 to 95, such as 20 to 95 and including 30 to 90. In someinstances, the pigments have an a* value ranging from −30 to 30, such as−25 to 25. In some instances, the pigments have a b* value ranging from−20 to 50, such as −15 to 45. The cool pigments may appear to have avariety of different colors, where the colors include, but are notlimited to: blacks, grays, browns, violets, purples, blues, teals,greens, yellows, oranges, pinks, reds, etc. The product material may, insome instances, be a cool pigment composition, e.g., as described in PCTPatent Application Serial No. US2015/047408 filed on Aug. 29, 2014; thedisclosure of which is herein incorporated by reference. In theseinstances, various color imparting additives may be introduced into theflowing liquid, where such additives may result in the production of oneor more transition metal carbonate materials. By transition metalcarbonate material is meant a composition made up of one or moretransition metal carbonate compounds, e.g., a composition that includestransition metal carbonate molecules, where the composition may includea single type of transition metal carbonate or two or more differenttypes of transition metal carbonates, e.g., that differ from each otherin terms of the transition metal ion component of the molecule. Thetransition metal carbonates may vary, and in some instances are period 4transition metal carbonates, by which is meant that they are carbonatesof period 4 transition metals, where period 4 transition metals ofinterest include, but are not limited to: Mn, Fe, Ni, Cu, Co, Zn.Specific period 4 transition metal carbonates that may be present in thetransitional metal carbonate materials include, but are not limited to:MnCO₃, FeCO₃, NiCO₃, CuCO₃, CoCO₃, ZnCO₃, etc., as well as combinationsthereof, e.g., (TM)_(m)(CO₃)_(n)), wherein TM is a transition metal(e.g., Mn,Fe,Co,Zn,Cu,Ni), and m and n are stoichiometric positiveintegers. Such color imparting additives include, but are not limitedto, those described in PCT Patent Application Serial No. US2015/047408filed on Aug. 29, 2014; the disclosure of which is herein incorporatedby reference.

In some instances, the method includes producing the solid phase CO₂sequestering carbonate material in association with a seed structure. Byseed structure is meant a solid structure or material that is present inthe flowing liquid, e.g., in the material production zone, prior todivalent cation introduction into the liquid. By “in association with”is meant that the material is produced on at least one of a surface ofor in a depression, e.g., a pore, crevice, etc., of the seed structure.In such instances, a composite structure of the carbonate material andthe seed structure is produced. In some instances, the product carbonatematerial coats a portion, if not all of, the surface of a seedstructure. In some instances, the product carbonate materials fills in adepression of the seed structure, e.g., a pore, crevice, fissure, etc.

Seed structures may vary widely as desired. The term “seed structure” isused to describe any object upon and/or in which the product carbonatematerial forms. Seed structures may range from singular objects orparticulate compositions, as desired. Where the seed structure is asingular object, it may have a variety of different shapes, which may beregular or irregular, and a variety of different dimensions. Shapes ofinterest include, but are not limited to, rods, meshes, blocks, etc.

In some instances, the seed structure is a particulate composition,e.g., granular composition, made up of a plurality of particles. Wherethe seed structure is a particulate composition, the dimensions ofparticles making up the seed structure may vary, ranging in someinstances from 0.01 to 1,000,000 μm, such as 0.1 to 100,000 μm. Thenumber of particles in the seed structure may also vary, ranging in someinstances from 5 to 5 trillion, such as 50 to 1 trillion, e.g., 100 to100 billion, etc., where in some instances the number of particlesmaking up the seed structure is 1,000 or more, such as 10,000 or more,including 100,000 or more, e.g., 1,000,000 or more.

The seed structure may be made up of any convenient material ormaterials. Materials of interest include both carbonate materials, suchas described above, as well as non-carbonate materials. The seedstructures may be naturally occurring, e.g., naturally occurring sands,shell fragments from oyster shells or other carbonate skeletalallochems, gravels, etc., or man-made, such as pulverized rocks, groundblast furnace slag, fly ash, cement kiln dust, red mud, and the like.For example, the seed structure may be a granular composition, such assand, which is coated with the carbonate material during the process,e.g., a white carbonate material or colored carbonate material, e.g., asdescribed above.

In some instances, seed structure may be coarse aggregates, such asfriable Pleistocene coral rock, e.g., as may be obtained from tropicalareas (e.g., Florida) that are too weak to serve as aggregate forconcrete. In this case the friable coral rock can be used as a seed, andthe solid CO₂ sequestering carbonate mineral may be deposited in theinternal pores, making the coarse aggregate suitable for use inconcrete, allowing it to pass the LA Rattler abrasion test. In someinstances, where a light weight aggregate is desired, the outer surfacewill only be oenetrated by the solution of deposition, leaving the innercore relatively ‘hollow’ making a light weight aggregate for use inlight weight concrete.

In methods where seed structures are employed, the flowing liquid withadded divalent cation source may be contacted with the seed structuresusing a variety of different protocols. In some protocols, the seedstructures are completely submerged in the flowing liquid, e.g., wherethe seed structures are submerged in a stream of the flowing liquid,etc. In some protocols, the seed structures are not submerged in theflowing liquid, e.g., where the flowing liquid may be flowed over asurface of the seed structures. For example, the flowing liquid may becontacted with the seed structures in a manner that results in theproduction of a thin layer of the flowing liquid on one or more surfacesof the seed structures. Such non-submerged approaches result, in someinstances, in one or more of: increased rate of reaction as compared tosubmerged protocols (e.g., by ensuring non-dilutive chemistry);increased reaction as compared to submerged protocols, e.g., by way ofhigher gas liquid interface and CO₂ off-gassing; enhanced energyefficiency as compared to submerged protocols, e.g., since suchprotocols may avoid having to use agitation mechanisms (such as trammel,etc.). In some non-submerged embodiments, low mM carbon bearingsolutions may be employed and efficient carbon capture on reasonableamounts of aggregate may be obtained. For example, non-submergedprotocols may be employed in large scale light weight aggregateproduction, where the calcium bearing and carbon bearing solutions couldbe distributed (drip irrigated distributed) over a field or large lyftedpile of rock, and the carbonate coating formed as the liquids percolatedown into and throughout the bed of aggregate.

Methods as described herein may be carried out in a variety of differentcontinuous reactors. Examples of continuous reactors of interest arefurther described below and in the Experimental section. Where acontinuous reactor is employed, the location at which the CO₂sequestering material is produced may be a fluidized bed subunit of thecontinuous reactor. Fluidized bed reactors of interest are configured tomaintain a region of fluidized solids in a continuously flowing medium,and may have a fluid inlet, a fluid outlet, and a region of materialproduction positioned there-between, A given fluidized bed reactor mayhave a single chamber or multiple chambers, as desired. An example of afluidized bed reactor is seen in FIG. 1. As shown in FIG. 1, flowingliquid enters the reactor (in flow) and the four chambers thereof, wherethe chambers include particulate seed structures, e.g., as describedabove. The flowing liquid entering the reactor includes an addeddivalent cation source, e.g., as described above. Seed structurecontacted liquid flows out of the top of the multiple chambers(outflow). Where desired, the fluidized bed may include structures,e.g., filters, meshes, frits, etc., or other retaining structures whichserve to keep the product material in the fluidize bed.

Methods as described herein may further include separating thenon-slurry solid phase CO₂ sequestering carbonate material from theaqueous bicarbonate rich product containing liquid. Any convenientseparation protocol may be employed to remove the product material fromthe liquid. As such, the product material may be pulled out of theliquid, the liquid may be drained from the product material, etc., asdesired. In some instances, the material is removed from the liquidwhile the liquid is still moving. In yet other instances the material isremoved from the liquid after movement of the liquid has been stopped.Compared with protocols that produce slurry products, the energyassociated with drying the product materials produced according to themethods described herein is much lower. While the magnitude ofdifference in energy usage may vary, in some instances the differenceranges from 2 to 100 times, such as 10 to 50 times per ton of materialproduced. One specific challenge inherent to the field of CO₂sequestering material production is reducing the amount of energyconsumed during the carbonation of CO₂. Common extraneous sources ofenergy use in production methods that produce a CO₂ sequesteringprecipitate material include the removal of water from the precipitatedmaterials after formation. Reducing energy needs normally required toseparate and potentially dry precipitated material form the bulksolution is important. As compared to process in which CO₂ sequesteringprecipitate materials are produced, embodiments of the present methodsproduce dried tons of CO₂ sequestering material using 2 to 100 timesless energy, such as 10 to 50 times less energy, in the waterseparation/drying step.

Production of Bicarbonate Rich Product Containing Liquid

In some instances, the method further includes producing the bicarbonaterich product containing liquid that is employed, e.g., as describedabove. Aspects of such protocols include contacting a CO₂ containing gaswith an aqueous medium to remove CO₂ from the CO₂ containing gas. TheCO₂ containing gas may be pure CO₂ or be combined with one or more othergasses and/or particulate components, depending upon the source, e.g.,it may be a multi-component gas (i.e., a multi-component gaseousstream). In certain embodiments, the CO₂ containing gas is obtained froman industrial plant, e.g., where the CO₂ containing gas is a waste feedfrom an industrial plant. Industrial plants from which the CO₂containing gas may be obtained, e.g., as a waste feed from theindustrial plant, may vary. Industrial plants of interest include, butare not limited to, power plants and industrial product manufacturingplants, such as but not limited to chemical and mechanical processingplants, refineries, cement plants, steel plants, etc., as well as otherindustrial plants that produce CO₂ as a byproduct of fuel combustion orother processing step (such as calcination by a cement plant). Wastefeeds of interest include gaseous streams that are produced by anindustrial plant, for example as a secondary or incidental product, of aprocess carried out by the industrial plant.

Of interest in certain embodiments are waste streams produced byindustrial plants that combust fossil fuels, e.g., coal, oil, naturalgas, as well as man-made fuel products of naturally occurring organicfuel deposits, such as but not limited to tar sands, heavy oil, oilshale, etc. In certain embodiments, power plants are pulverized coalpower plants, supercritical coal power plants, mass burn coal powerplants, fluidized bed coal power plants, gas or oil-fired boiler andsteam turbine power plants, gas or oil-fired boiler simple cycle gasturbine power plants, and gas or oil-fired boiler combined cycle gasturbine power plants. Of interest in certain embodiments are wastestreams produced by power plants that combust syngas, i.e., gas that isproduced by the gasification of organic matter, e.g., coal, biomass,etc., where in certain embodiments such plants are integratedgasification combined cycle (IGCC) plants. Of interest in certainembodiments are waste streams produced by Heat Recovery Steam Generator(HRSG) plants. Waste streams of interest also include waste streamsproduced by cement plants. Cement plants whose waste streams may beemployed in methods of the invention include both wet process and dryprocess plants, which plants may employ shaft kilns or rotary kilns, andmay include pre-calciners. Each of these types of industrial plants mayburn a single fuel, or may burn two or more fuels sequentially orsimultaneously. A waste stream of interest is industrial plant exhaustgas, e.g., a flue gas. By “flue gas” is meant a gas that is obtainedfrom the products of combustion from burning a fossil or biomass fuelthat are then directed to the smokestack, also known as the flue of anindustrial plant.

In sequestering CO₂ from a CO₂-containing gas, a CO₂-containing gas maybe contacted with an aqueous medium under conditions sufficient toremove CO₂ from the CO₂-containing gas and produce a bicarbonatecomponent, which bicarbonate component may then be contacted with acation source to produce a substantially pure CO₂ product gas and acarbonate CO₂ sequestering component, e.g., as described in greaterdetail below.

The aqueous medium may vary, ranging from fresh water to bicarbonatebuffered aqueous media. Bicarbonate buffered aqueous media employed inembodiments of the invention include liquid media in which a bicarbonatebuffer is present. As such, liquid aqueous media of interest includedissolved CO₂, water, carbonic acid (H₂CO₃), bicarbonate ions (HCO₃ ⁻),protons (H⁺) and carbonate ions (Co₃ ²⁻). The constituents of thebicarbonate buffer in the aqueous media are governed by the equation:

CO₂+H₂O

H₂CO₃

H⁺+HCO₃ ⁻

2H⁺+CO₃ ²⁻

The pH pH of the bicarbonate buffered aqueous media may vary, ranging insome instances from 7 to 11, such as 8 to 11, e.g., 8 to 10, including 8to 9. In some instances, the pH ranges from 8.2 to 8.7, such as from 8.4to 8.55. The bicarbonate buffered aqueous medium may be a naturallyoccurring or man-made medium, as desired. Naturally occurringbicarbonate buffered aqueous media include, but are not limited to,waters obtained from seas, oceans, lakes, swamps, estuaries, lagoons,brines, alkaline lakes, inland seas, etc. Man-made sources ofbicarbonate buffered aqueous media may also vary, and may include brinesproduced by water desalination plants, and the like. Of interest in someinstances are waters that provide for excess alkalinity, which isdefined as alkalinity that is provided by sources other than bicarbonateion. In these instances, the amount of excess alkalinity may vary, solong as it is sufficient to provide 1.0 or slightly less, e.g., 0.9,equivalents of alkalinity. Waters of interest include those that provideexcess alkalinity (meq/liter) of 30 or higher, such as 40 or higher, 50or higher, 60 or higher, 70 or higher, 80 or higher, 90 or higher, 100or higher, etc. Where such waters are employed, no other source ofalkalinity, e.g., NaOH, is required.

In some instances, the aqueous medium that is contacted with the CO₂containing gas is one which, in addition to the bicarbonate bufferingsystem (e.g., as described above), further includes an amount ofdivalent cations. Inclusion of divalent cations in the aqueous mediumcan allow the concentration of bicarbonate ion in the bicarbonate richproduct to be increased, thereby allowing a much larger amount of CO₂ tobecome sequestered as bicarbonate ion in the bicarbonate rich product.In such instances, bicarbonate ion concentrations that exceed 5,000 ppmor greater, such as 10,000 ppm or greater, including 15,000 ppm orgreater may be achieved. For instance, calcium and magnesium occur inseawater at concentrations of 400 and 1200 ppm respectively. Through theformation of a bicarbonate rich product using seawater (or an analogouswater as the aqueous medium), bicarbonate ion concentrations that exceed10,000 ppm or greater may be achieved.

In such embodiments, the total amount of divalent cation source in themedium, which divalent cation source may be made up of a single divalentcation species (such as Ca²⁺) or two or more distinct divalent cationspecies (e.g., Ca²⁺, Mg²⁺, etc.), may vary, and in some instances is 100ppm or greater, such as 200 ppm or greater, including 300 ppm orgreater, such as 500 ppm or greater, including 750 ppm or greater, suchas 1,000 ppm or greater, e.g., 1,500 ppm or greater, including 2,000 ppmor greater. Divalent cations of interest that may be employed, eitheralone or in combination, as the divalent cation source include, but arenot limited to: Ca²⁺, Mg²⁺, Be²⁺, Ba²⁺, Sr²⁺, Pb²⁺, Fe²⁺, Hg²⁺ and thelike. Other cations of interest that may or may not be divalent include,but are not limited to: Na⁺, K⁺, NH⁴⁺, and Li⁺, as well as cationicspecies of Mn, Ni, Cu, Zn, Cu, Ce, La, Al, Y, Nd, Zr, Gd, Dy, Ti, Th, U,La, Sm, Pr, Co, Cr, Te, Bi, Ge, Ta, As, Nb, W, Mo, V, etc. Naturallyoccurring aqueous media which include a cation source, divalent orotherwise, and therefore may be employed in such embodiments include,but are not limited to: aqueous media obtained from seas, oceans,estuaries, lagoons, brines, alkaline lakes, inland seas, etc.

In some instances, the aqueous medium is one that has been subjected toan alkali enrichment (AE) process, such as a membrane mediated alkalienrichment process. In such instances, prior to contact with the CO₂containing gas, the aqueous medium is subjected to a process thatresults in an increase in the pH of the aqueous medium. Of interest aremembrane mediated processes, such as forward osmosis mediated process.Alkali enrichment processes of interest include, but are not limited to,those described in PCT Application Serial No. PCT/US2015/018361 nowpublished as WO 2015/134408; the disclosure of which is hereinincorporated by reference.

Contact of the CO₂ containing gas and bicarbonate buffered aqueousmedium may be done under conditions sufficient to remove CO₂ from theCO₂ containing gas (i.e., the CO₂ containing gaseous stream), andincrease the bicarbonate ion concentration of the buffered aqueousmedium to produce a bicarbonate rich product. The CO₂ containing gas maybe contacted with the aqueous medium using any convenient protocol. Forexample, contact protocols of interest include, but are not limited to:direct contacting protocols, e.g,, bubbling the gas through a volume ofthe aqueous medium, concurrent contacting protocols, i.e., contactbetween unidirectionally flowing gaseous and liquid phase streams,countercurrent protocols, i.e., contact between oppositely flowinggaseous and liquid phase streams, and the like. Contact may beaccomplished through use of infusers, bubblers, fluidic Venturireactors, spargers, gas filters, sprays, trays, or packed columnreactors, and the like, as may be convenient. The process may be a batchor continuous process.

Contact occurs under conditions such that a substantial portion of theCO₂ present in the CO₂ containing gas goes into solution to producebicarbonate ions. In some instances, 5% or more, such as 10% or more,including 20% or more of all the bicarbonate ions in the initialexpanded liquid phase solution (mother liquor) become sequestered inLCPs. Where desired, the CO₂ containing gas is contacted with thebicarbonate buffered aqueous medium in the presence of a catalyst (i.e.,an absorption catalyst) that mediates the conversion of CO₂ tobicarbonate. Catalysts of interest are further described in U.S. patentapplication Ser. No. 14/112,495; the disclosure of which is hereinincorporated by reference.

Contact between the alkaline aqueous medium and the CO₂-containing gasresults in the production of a DIC containing liquid. As such, incharging the CO₂ capture liquid with CO₂, a CO₂ containing gas may becontacted with CO₂ capture liquid under conditions sufficient to producedissolved inorganic carbon (DIC) in the CO₂ capture liquid , i.e., toproduce a DIC containing liquid. The DIC is the sum of theconcentrations of inorganic carbon species in a solution, represented bythe equation: DIC=[CO₂*]+[HCO₃ ⁻]+[CO₃ ²⁻], where [CO₂*] is the sum ofcarbon dioxide ([CO₂]) and carbonic acid ([H₂CO₃]) concentrations, [HCO₃⁻] is the bicarbonate concentration and [CO₃ ²⁻] is the carbonateconcentration in the solution. The DIC of the aqueous media may vary,and in some instances may be 5,000 ppm or greater, such as 10,000 ppm orgreater, including 15,000 ppm or greater. In some instances, the DIC ofthe aqueous media may range from 5,000 to 20,000 ppm, such as 7,500 to15,000 ppm, including 8,000 to 12,000 ppm. The amount of CO₂ dissolvedin the liquid may vary, and in some instances ranges from 0.05 to 40 mM,such as 1 to 35 mM, including 25 to 30 mM. The pH of the resultant DICcontaining liquid may vary, ranging in some instances from 4 to 12, suchas 6 to 11 and including 7 to 10, e.g., 8 to 8.5.

Where desired, following production of the LCP containing liquid, theresultant LCP containing liquid may be manipulated to increase theamount or concentration of LCP droplets in the liquid. As such,following production of the bicarbonate containing liquid, thebicarbonate containing liquid may be further manipulated to increase theconcentration of bicarbonate species and produce a concentratedbicarbonate liquid. In some instances, the bicarbonate containing liquidis manipulated in a manner sufficient to increase the pH. In suchinstances, the pH may be increased by an amount ranging from 0.1 to 6 pHunits, such as 1 to 3 pH units. The pH of the concentrated bicarbonateliquid of such as step may vary, ranging in some instances from 5.0 to13.0, such as 6.5 to 8.5. The concentration of bicarbonate species inthe concentrated bicarbonate liquid may vary, ranging in some instancesfrom 1 to 1000 mM, such as 20 to 200 mM and including 50 to 100 mM. Insome instances, the concentrated bicarbonate liquid may further includean amount of carbonate species. While the amount of carbonate speciesmay vary, in some instances the carbonate species is present in anamount ranging from 0.01 to 800 mM, such as 10 to 100 mM,

The pH of the bicarbonate liquid may be increased using any convenientprotocol. In some instances, an electrochemical protocol may be employedto increase the pH of the bicarbonate liquid to produce the concentratedbicarbonate liquid. Electrochemical protocols may vary, and in someinstances include those employing an ion exchange membrane andelectrodes, e.g., as described in U.S. Pat. Nos. 8,357,270; 7,993,511;7,875,163; and 7,790,012; the disclosures of which are hereinincorporated by reference. Alkalinity of the bicarbonate containingliquid may also be accomplished by adding a suitable amount of achemical agent to the bicarbonate containing liquid. Chemical agents foreffecting proton removal generally refer to synthetic chemical agentsthat are produced in large quantities and are commercially available.For example, chemical agents for removing protons include, but are notlimited to, hydroxides, organic bases, super bases, oxides, ammonia, andcarbonates. Hydroxides include chemical species that provide hydroxideanions in solution, including, for example, sodium hydroxide (NaOH),potassium hydroxide (KOH), calcium hydroxide (Ca(OH)₂), or magnesiumhydroxide (Mg(OH)₂). Organic bases are carbon-containing molecules thatare generally nitrogenous bases including primary amines such as methylamine, secondary amines such as diisopropylamine, tertiary such asdiisopropylethylamine, aromatic amines such as aniline, heteroaromaticssuch as pyridine, imidazole, and benzimidazole, and various formsthereof. In some embodiments, an organic base selected from pyridine,methylamine, imidazole, benzimidazole, histidine, and a phophazene isused to remove protons from various species (e.g., carbonic acid,bicarbonate, hydronium, etc.) for precipitation of precipitationmaterial. In some embodiments, ammonia is used to raise pH to a levelsufficient to precipitate precipitation material from a solution ofdivalent cations and an industrial waste stream. Super bases suitablefor use as proton-removing agents include sodium ethoxide, sodium amide(NaNH₂), sodium hydride (NaH), butyl lithium, lithium diisopropylamide,lithium diethylamide, and lithium bis(trimethylsilyl)amide. Oxidesincluding, for example, calcium oxide (CaO), magnesium oxide (MgO),strontium oxide (SrO), beryllium oxide (BeO), and barium oxide (BaO) arealso suitable proton-removing agents that may be used.

Another type of further manipulation following production that may beemployed is a dewatering of the initial bicarbonate containing liquid toproduce a concentrated bicarbonate containing liquid, e.g., aconcentrated LCP liquid. Dewatering may be accomplished using anyconvenient protocol, such as via contacting the LCP composition with asuitable membrane, such as an ultrafiltration membrane, to remove waterand certain species, e.g., NaCl, HCl, H₂CO₃ but retain LCP droplets,e.g., as described in greater detail in U.S. application Ser. No.14/112,495; the disclosure of which is herein incorporated by reference

Production of Materials from the CO₂ Sequestering Carbonate Product

The product carbonate material may be further manipulated and/orcombined with other compositions to produce a variety of end-usematerials. In certain embodiments, the product carbonate composition isrefined (i.e., processed) in some manner. Refinement may include avariety of different protocols. In certain embodiments, the product issubjected to mechanical refinement, e.g., grinding, in order to obtain aproduct with desired physical properties, e.g., particle size, etc. Incertain embodiments, the product is combined with a hydraulic cement,e.g., as a sand, a gravel, as an aggregate, etc., e.g,, to produce finalproduct, e,g., concrete or mortar.

Also of interest are formed building materials. The formed buildingmaterials of the invention may vary greatly. By “formed” is meantshaped, e.g., molded, cast, cut or otherwise produced, into a man-madestructure defined physical shape, i.e., configuration. Formed buildingmaterials are distinct from amorphous building materials, e.g.,particulate (such as powder) compositions that do not have a defined andstable shape, but instead conform to the container in which they areheld, e.g., a bag or other container. Illustrative formed buildingmaterials include, but are not limited to: bricks; boards; conduits;beams; basins; columns; drywalls etc. Further examples and detailsregarding formed building materials include those described in UnitedStates Published Application No. US20110290156; the disclosure of whichis herein incorporated by reference.

Also of interest are non-cementitious manufactured items that includethe product of the invention as a component, Non-cementitiousmanufactured items of the invention may vary greatly. Bynon-cementitious is meant that the compositions are not hydrauliccements. As such, the compositions are not dried compositions that, whencombined with a setting fluid, such as water, set to produce a stableproduct. Illustrative compositions include, but are not limited to:paper products; polymeric products; lubricants; asphalt products;paints; personal care products, such as cosmetics, toothpastes,deodorants, soaps and shampoos; human ingestible products, includingboth liquids and solids; agricultural products, such as soil amendmentproducts and animal feeds; etc. Further examples and detailsnon-cementitious manufactured items include those described in U.S. Pat.No. 7,829,053; the disclosure of which is herein incorporated byreference.

In some instances, the solid carbonate product may be employed in albedoenhancing applications. Albedo, i.e., reflection coefficient, refers tothe diffuse reflectivity or reflecting power of a surface. It is definedas the ratio of reflected radiation from the surface to incidentradiation upon it. Albedo is a dimensionless fraction, and may beexpressed as a ratio or a percentage. Albedo is measured on a scale fromzero for no reflecting power of a perfectly black surface, to 1 forperfect reflection of a white surface. While albedo depends on thefrequency of the radiation, as used herein Albedo is given withoutreference to a particular wavelength and thus refers to an averageacross the spectrum of visible light, i.e., from about 380 to about 740nm.

As the methods of these embodiments are methods of enhancing albedo of asurface, the methods in some instances result in a magnitude of increasein albedo (as compared to a suitable control, e.g., the albedo of thesame surface not subjected to methods of invention) that is .05 orgreater, such as 0.1 or greater, e.g., 0.2 or greater, 0.3 or greater,0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 orgreater, 0.9 or greater, including 0.95 or greater, including up to 1.0.As such, aspects of the subject methods include increasing albedo of asurface to 0.1 or greater, such as 0.2 or greater, e.g., 0.3 or greater,0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 orgreater, 0.9 or greater, 0.95 or greater, including 0.975 or greater andup to approximately 1.0.

Aspects of the methods include associating with a surface of interest anamount of a highly reflective microcrystalline or amorphous materialcomposition effective to enhance the albedo of the surface by a desiredamount, such as the amounts listed above. The material composition maybe associated with the target surface using any convenient protocol. Assuch, the material composition may be associated with the target surfaceby incorporating the material into the material of the object having thesurface to be modified. For example, where the target surface is thesurface of a building material, such as a roof tile or concrete mixture,the material composition may be included in the composition of thematerial so as to be present on the target surface of the object.Alternatively, the material composition may be positioned on at least aportion of the target surface, e.g., by coating the target surface withthe composition. Where the surface is coated with the materialcomposition, the thickness of the resultant coating on the surface mayvary, and in some instances may range from 0.1 mm to 25 mm, such as 2 mmto 20 mm and including 5 mm to 10 mm. Applications in use as highlyreflective pigments in paints and other coatings like photovoltaic solarpanels are also of interest.

The albedo of a variety of surfaces may be enhanced. Surfaces ofinterest include at least partially facing skyward surfaces of bothman-made and naturally occurring objects. Man-made surfaces of interestinclude, but are not limited to: roads, sidewalks, buildings andcomponents thereof, e.g., roofs and components thereof (roof shingles,roofing granules, etc.) and sides, runways, and other man-madestructures, e.g., walls, dams, monuments, decorative objects, etc.Naturally occurring surfaces of interest include, but are not limitedto: plant surfaces, e.g., as found in both forested and non-forestedareas, non-vegetated locations, water, e.g., lake, ocean and seasurfaces, etc.

For example, the albedo of colored granules may be readily increasedusing methods as described herein to produce a carbonate layer on thesurface of the colored roofing granules. While the thickness of thelayer of carbonate material present on the surface of the coloredroofing granules may vary, in some instances the thickness ranges from0.1 to 200 μm, such as 1 to 150 μm, including 5 to 100 μm. A variety ofdifferent types of colored granules may be coated as described above,e.g., to enhance their reflectivity without substantially diminishingtheir color, if at all. Examples of types of granules that may be coatedwith a carbonate layer as described herein include roofing granules.

Roofing granules that may be coated with a carbonate layer, e.g., toimprove their reflectivity without substantially reducing their color,if at all, may include a core formed by crushed and screened mineralmaterials, which are subsequently coated with one or more color coatinglayers comprising a binder in which is dispersed one or more coloringpigments, such as suitable metal oxides. Inorganic binders may beemployed. The binder can be a soluble alkaline silicate that issubsequently insolubilized by heat or by chemical reaction, such as byreaction between an acidic material and the alkaline silicate, resultingin an insoluble colored coating on the mineral particles. The baseparticles employed in the process of preparing the roofing granules ofthe present invention can take several forms. The base particles may beinert core particles. The core particles may be chemically inertmaterials, such as inert mineral particles, solid or hollow glass orceramic spheres, or foamed glass or ceramic particles. Suitable mineralparticles can be produced by a series of quarrying, crushing, andscreening operations, are generally intermediate between sand and gravelin size (that is, between about #8 US mesh and #70 US mesh). The coreparticles have an average particle size of from about 0.2 mm to about 3mm, e.g., from about 0.4 mm to about 2.4 mm. In particular, suitablysized particles of naturally occurring materials such as talc, slag,granite, silica sand, greenstone, andesite, porphyry, marble, syenite,rhyolite, diabase, greystone, quartz, slate, trap rock, basalt, andmarine shells can be used, as well as manufactured materials such asceramic grog and proppants, and recycled manufactured materials such ascrushed bricks, concrete, porcelain, fire clay, and the like. Solid andhollow glass spheres are available, for example, from Potters IndustriesInc., P.O. Box 840, Valley Forge, Pa. 19482-0840, such as SPHERIGLASS®solid “A” glass spheres product grade 1922 having a mean size of 0.203mm, product code 602578 having a mean size of 0.59 mm, BALLOTTINI impactbeads product grade A with a size range of 600 to 850 micrometers (U.S.Seive size 20-30), and QCEL hollow spheres, product code 300 with a meanparticle size of 0.090 mm. Glass spheres can be coated or treated with asuitable coupling agent if desired for better adhesion to the binder ofthe inner coating composition. In the granules, the particles can becoated with a coating composition that includes binder and a pigment.The coating binder can be an inorganic material, such as ametal-silicate binder, for example an alkali metal silicate, such assodium silicate.

The coatings pigments that may be used include, but are not limited toPC-9415 Yellow, PC-9416 Yellow, PC-9158 Autumn Gold, PC-9189 BrightGolden Yellow, V-9186 Iron-Free Chestnut Brown, V-780 Black, V0797 IRBlack, V-9248 Blue, PC-9250 Bright Blue, PC-5686 Turquoise, V-13810 Red,V-12600 Camouflage Green, V12560 IR Green, V-778 IR Black, and V-799Black.

Methods as described herein may also be employed to produce frac sands.Frac-sands are used in the oil and gas recovery industry to maintainporous void space in fractured geologic structure, so as to maintaingeologic fracture integrity. Methods described herein may be employed toproduce coated substrates and manufactured sands with tailorable surfacecoatings that can contribute to the buoyancy of the sand when in fluidflow. Methods as described herein may be employed to produce substratewith a closely regular patterning or irregular patterning of carbonatematerials (crystalline or amorphous) as to effectively design thesurface of the sands to maintain an above average buoyancy in the flowof fracking fluid, while the fluids are being pumped under very highpressure into the geologic fracture site. In some instances, the methodsproduce a product with a crystalline or amorphous however unreactedcementitious coating compound, such that upon contact with a secondmedium, the material could react as an expansive cement, providing voidspace for gas and fluid flow from surrounding geologic structure. Thisexpansive property could be activated by intimate fluid or gas contact,sustained fluid contact, or other magnetic or sound wave activationprovided from the geologic surface.

Methods of using the carbonate precipitate compounds described herein invarying applications as described above, including albedo enhancingapplications, as well as compositions produced thereby, are furtherdescribed in U.S. application Ser. Nos. 14/112,495 and 14/214,129; thedisclosures of which applications are herein incorporated by reference.

Production of Pure CO₂ Gas

During the production of solid carbonate compositions from thebicarbonate rich product or component thereof (e.g., LCP), one mol ofCO₂ may be produced for every 2 cools of bicarbonate ion from thebicarbonate rich product or component thereof (e.g., LCP). For example,where solid carbonate compositions are produced by adding calcium cationto the bicarbonate rich product or component thereof (e.g., LCP), theproduction of solid carbonate compositions, e.g., the form of amorphouscalcium carbonate minerals, may proceed according to the followingreaction:

2HCO₃ ⁻+Ca⁺⁺↔CaCO₃.H₂O+CO₂

Ca⁺⁺ _((aq))+2HCO_(3(aq)) ⁻↔CaCO_(3(s))+H₂O_((f)+CO) _(2(g))

While the above reaction shows the production of 1 mol of CO₂, 2 molesof CO₂ from the CO₂ containing gas were initially converted tobicarbonate. As such, the overall process sequesters a net 1 mol of CO₂in a carbonate compound and produces 1 mol of substantially pure CO₂product gas, which may be sequestered by injection into a subsurfacegeological location, as described in greater detail below. Therefore,the process is an effective CO₂ sequestration process. Contact of thebicarbonate rich product with the cation source results in production ofa substantially pure CO₂ product gas. The phrase “substantially pure”means that the product gas is pure CO₂ or is a CO₂ containing gas thathas a limited amount of other, non-CO₂ components.

Following production of the CO₂ product gas, aspects of the inventionmay include injecting the product CO₂ gas into a subsurface geologicallocation to sequester CO₂. By injecting is meant introducing or placingthe CO₂ product gas into a subsurface geological location. Subsurfacegeological locations may vary, and include both subterranean locationsand deep ocean locations. Subterranean locations of interest include avariety of different underground geological formations, such as fossilfuel reservoirs, e.g., oil fields, gas fields and un-mineable coalseams; saline reservoirs, such as saline formations and saline-filledbasalt formations; deep aquifers; porous geological formations such aspartially or fully depleted oil or gas formations, salt caverns, sulfurcaverns and sulfur domes; etc.

In some instances, the CO₂ product gas may be pressurized prior toinjection into the subsurface geological location. To accomplish suchpressurization the gaseous CO₂ can be compressed in one or more stageswith, where desired, after cooling and condensation of additional water.The modestly pressurized CO₂ can then be further dried, where desired,by conventional methods such as through the use of molecular sieves andpassed to a CO₂ condenser where the CO₂ is cooled and liquefied. The CO₂can then be efficiently pumped with minimum power to a pressurenecessary to deliver the CO₂ to a depth within the geological formationor the ocean depth at which CO₂ injection is desired. Alternatively, theCO₂ can be compressed through a series of stages and discharged as asuper critical fluid at a pressure matching that necessary for injectioninto the geological formation or deep ocean. A/here desired, the CO₂ maybe transported, e.g., via pipeline, rail, truck or other suitableprotocol, from the production site to the subsurface geologicalformation.

In some instances, the CO₂ product gas is employed in an enhanced oilrecovery (EOR) protocol. Enhanced Oil Recovery (abbreviated EOR) is ageneric term for techniques for increasing the amount of crude oil thatcan be extracted from an oil field. Enhanced oil recovery is also calledimproved oil recovery or tertiary recovery. In EOR protocols, the CO₂product gas is injected into a subterranean oil deposit or reservoir.

CO₂ gas production and sequestration thereof is further described inU.S. application Ser. No. 14/861,996, the disclosure of which is hereinincorporated by reference.

Recycling

In some instances, the methods may include recirculating one or more ofthe reaction components through the material production zone. Forexample, the aqueous bicarbonate rich liquid, e.g., LCP containingliquid, may be recirculated through the material production zone. Insuch instances, an amount of fresh aqueous bicarbonate liquid may becombined with the recycled liquid to provide for desired flow throughthe production zone.

Systems

Aspects of the invention further include systems, e.g., small scaledevices, processing plants or factories, for producing CO₂ sequesteringcarbonate materials, e.g., by practicing methods as described above.Systems of the invention may have any configuration that enablespractice of the particular sequestration material production method ofinterest. Systems of the invention include continuous reactors that areconfigured for producing CO₂ sequestering carbonate materials. As thesystems includes continuous reactors (i.e., flow reactors), they includereactors in which materials are carried in a flowing stream, wherereactants (e.g., divalent cations, aqueous bicarbonate rich liquid,etc.) are continuously fed into the reactor and emerge as continuousstream of product. The continuous reactor components of the systems aretherefore not batch reactors. A given system may include the continuousreactors, e.g., as described herein, in combination with one or moreadditional elements, as described in greater detail below.

In some embodiments, continuous reactors of the systems include: aflowing aqueous liquid, e.g., a bicarbonate rich product containingliquid; a divalent cation introducer configured to introduce divalentcations at an introduction location into the flowing aqueous liquid; anda non-slurry solid phase CO₂ sequestering carbonate material productionlocation which is located at a distance from the divalent cationintroducer. The flowing aqueous liquid is a stream of moving aqueousliquid, e.g., as described above, which may be present in the continuousreactor, where the continuous reactor may have any convenientconfiguration. Continuous reactors of interest include an inlet for aliquid and an outlet for the waste liquid, where the inlet and outletare arranged relative to each other to provide for continuous movementor flow of the liquid into and out of the reactor. The reactor may haveany convenient structure, where in some instances the reactor may have alength along which the liquid flows that is longer than any given crosssectional dimension of the reactor, where the inlet is at a first end ofthe reactor and the outlet is at a second end of the reactor. The volumeof the reactor may vary, ranging in some instances from 10 L to1,000,000 L, such as 1,000 L to 100,000 L.

Continuous reactors of interest further include a divalent cationintroducer configured to introduce divalent cations at an introductionlocation into the flowing aqueous liquid. Any convenient introducer maybe employed, where the introducer may be a liquid phase or solid phaseintroducer, depending on the nature of the divalent cation source. Theintroducer may be located in some instances at substantially the same,if not the same, position as the inlet for the bicarbonate rich productcontaining liquid. Alternatively, the introducer may be located at adistance downstream from the inlet. In such instances, the distancebetween the inlet and the introducer may vary, ranging in someembodiments from 1 cm to 10 m, such as 10 cm to 1 m. The introducer maybe operatively coupled to a source or reservoir of divalent cations.

Continuous reactors of interest also include a non-slurry solid phaseCO₂ sequestering carbonate material production location. This locationis a region or area of the continuous reactor where a non-slurry solidphase CO₂ sequestering carbonate material is produced as a result ofreaction of the divalent cations with bicarbonate ions of thebicarbonate rich product containing liquid. The reactor may beconfigured to produce any of the non-slurry solid phase CO₂ sequesteringcarbonate materials described above in the production location. In someinstances, the production location is located at a distance from thedivalent cation introduction location. While this distance may vary, insome instances the distance between the divalent cation introducer andthe material production location ranges from 1 cm to 10 m, such as 10 cmto 1 m.

The production location may include seed structure(s), such as describedabove. In such instances, the reactor may be configured to contact theseed structures in a submerged or non-submerged format, such asdescribed above. In non-submerged formats, the flowing liquid may bepresent on the surface of seed structures as a layer, e.g., of varyingthickness, but a gas, e.g., air, separates at least two portions of theseed structure, e.g., two different particles, such that the particlesare not submerged in the liquid.

In some instances, the presence of non-slurry solid phase CO₂sequestering carbonate materials in the material production locationresults in the presence of a fluidized bed in the material productionlocation, wherein the solids of the fluidized bed include solid phaseCO₂ sequestering carbonate material(s), which solids may increase inmass over time as more CO₂ sequestering carbonate material(s) isproduced.

Where desired the reactor may further include a retaining structureconfigured to retain non-slurry solid phase CO₂ sequestering carbonatematerials in the material production location. Retaining structures ofinterest include filters, meshes or analogous structures (e.g., frits)which serve to maintain the non-slurry solid phase CO₂ sequesteringcarbonate materials in the production location despite the movement ofthe aqueous bicarbonate rich product containing liquid through theproduction location.

The reactor may have a flow modulator that is configured to maintain adesired flow rate of liquid through the reactor or portion thereof. Forexample, the flow modulator may be configured to maintain a constant anddesired rate of liquid flow through the reactor, or may be configured tovary the flow rate of the liquid through different portions of thereactor, such that the reactor may have a first flow rate in a firstportion and a second flow rate in a second portion. The flow modulatormay be configured to provide for liquid flow through the reactor a valueranging from 0.1 m/s to 10 m/s, such as 1 m/s to 5 m/s.

The reactor may have a pressure modulator that is configured to maintaina desired pressure in the reactor or portion thereof. For example, thepressure modulator may be configured to maintain a constant and desiredpressure throughout the reactor, or may be configured to vary thepressure in different portions of the reactor, such that the reactor mayhave a first pressure in a first portion and a second pressure in asecond portion. For example, the reactor may have a higher pressure inthe region of divalent cation introduction and a lower pressure in theregion of material production. In such instances, the difference inpressure between any two regions may vary, ranging in some instancesfrom 0.1 atm to 1,000 atm, such as 1 atm to 10 atm. The pressuremodulator may be configured to provide for pressure in the reactor at avalue ranging from 0.1 atm to 1,000 atm, such as 1 atm to 10 atm, whichmay vary among different regions of the reactor, e.g., as describedabove.

The reactor may have a temperature modulator that is configured tomaintain a desired temperature in the reactor or portion thereof. Forexample, the temperature modulator may be configured to maintain aconstant and desired temperature throughout the reactor, or may beconfigured to vary the temperature in different portions of the reactor,such that the reactor may have a first temperature in a first portionand a second temperature in a second portion of the reactor. Thetemperature modulator may be configured to provide for temperature inthe reactor having a value ranging from −4 to 99° C., such as 0 to 80°C.

The reactor may include an agitator, e.g., to stir or agitate thenon-slurry product during production. Any convenient type of agitatormay be employed, including, but not limited to, a trommel, a vibrationsource, etc.

In some instances, the continuous reactor, e.g., as described above, isoperatively coupled to an aqueous bicarbonate rich product containingliquid production unit. While such units may vary, in some instancessuch units include a source of the CO₂ containing gas; a source of anaqueous medium; and a reactor configured to contact the CO₂ containinggas with the aqueous medium under conditions sufficient to produce abicarbonate rich product. Any convenient bicarbonate buffered aqueousmedium source may be included in the system. In certain embodiments, thesource includes a structure having an input for aqueous medium, such asa pipe or conduit from an ocean, etc. Where the aqueous medium isseawater, the source may be an input that is in fluid communication withthe sea water, e.g., such as where the input is a pipe line or feed fromocean water to a land based system or an inlet port in the hull of ship,e.g., where the system is part of a ship, e.g., in an ocean basedsystem.

The CO₂ containing gas source may vary. Examples of CO₂ containing gassources include, but are not limited to, pipes, ducts, or conduits whichdirect the CO₂ containing gas to a portion of the system, e.g., to areactor configured to produce a bicarbonate rich product, e.g., thatincludes LCPs. The aqueous medium source and the CO₂ containing gassource are connected to a reactor configured to contact the CO₂containing gas with the bicarbonate buffered aqueous medium underconditions sufficient to produce a bicarbonate rich product, such asdescribed above. The reactor may include any of a number of components,such as temperature regulators (e.g., configured to heat the water to adesired temperature), chemical additive components, e.g., forintroducing agents that enhance bicarbonate production, mechanicalagitation and physical stirring mechanisms. The reactor may include acatalyst that mediates the conversion of CO₂ to bicarbonate, such asdescribed above. The reactor may also include components that allow forthe monitoring of one or more parameters such as internal reactorpressure, pH, metal-ion concentration, and PCO₂. The reactor furtherincludes an output conveyance for the bicarbonate rich product which isfluidically coupled, either directly or indirectly, to the inlet of thecontinuous reactor.

Reactors configured to produce aqueous bicarbonate rich productcontaining liquids are further described in U.S. application Ser. Nos.14/112,495 and 14/636,043, the disclosures of which are hereinincorporated by reference.

In certain embodiments, the system will further include a station (i.e.,a building material production unit) for preparing a building material,such as described above (e.g., a cement or roofing granules), from theproduct material. This station can be configured to produce a variety ofcements, aggregates, or cementitious materials from the material e.g.,as described in U.S. Pat. No. 7,735,274; the disclosure of whichapplication is herein incorporated by reference.

In addition, the system may include an output for the substantially pureproduct CO₂ gas that is produced in the reactor upon production of thesequestering material. The output may be operatively coupled to aninjector configured to inject the product CO₂ into a subsurfacegeological location, e.g., as described above. Where desired, the systemmay include a compressor and/or temperature modulator for the CO₂product gas, where such component, when present, are operativelypositioned between the output and the injector. As the injector andoutput are operatively coupled, they may be directly connected to eachother or connected via a conveyor, such as a pipeline.

Utility

The methods and systems described above find use in a variety ofdifferent applications, including CO₂ sequestration processes, i.e.,processes (methods, protocols, etc.) that result in CO₂ sequestration.By “CO₂ sequestration” is meant the removal or segregation of an amountof CO₂ from an environment, such as the Earth's atmosphere or a gaseouswaste stream produced by an industrial plant, so that some or all of theCO₂ is no longer present in the environment from which it has beenremoved. CO₂ sequestering methods of the invention sequester CO₂ byproducing a storage stable carbon dioxide sequestering product from anamount of CO₂, such that the CO₂ is sequestered, as well as asubstantially pure subsurface injectable CO₂ product gas. The storagestable CO₂ sequestering product is a storage stable composition thatincorporates an amount of CO₂ into a storage stable form, such as anabove-ground storage or underwater storage stable form, so that the CO₂is no longer present as, or available to be, a gas in the atmosphere.Sequestering of CO₂ according to methods of the invention results inprevention of CO₂ gas from entering the atmosphere and allows forlong-term storage of CO₂ in a manner such that CO₂ does not become partof the atmosphere.

Carbonate Coated Aggregates

As reviewed above, the methods and systems of the invention may beemployed to produce carbonate coated aggregates, e.g., for use inconcretes and other applications. The carbonate coated aggregates may beconventional or lightweight aggregates.

Aspects of the invention include CO₂ sequestering aggregatecompositions. The CO₂ sequestering aggregate compositions includeaggregate particles having a core and a CO₂ sequestering carbonatecoating on at least a portion of a surface of the core. The CO₂sequestering carbonate coating is made up of a CO₂ sequesteringcarbonate material, e.g., as described above.

The CO₂ sequestering carbonate material that is present in coatings ofthe coated particles of the subject aggregate compositions may vary.

In some instances, the carbonate material is a highly reflectivemicrocrystalline/amorphous carbonate material. Themicrocrystalline/amorphous materials present in coatings of theinvention may be highly reflective. As the materials may be highlyreflective, the coatings that include the same may have a high totalsurface reflectance (TSR) value. TSR may be determined using anyconvenient protocol, such as ASTM E1918 Standard Test Method forMeasuring Solar Reflectance of Horizontal and Low-Sloped Surfaces in theField (see also R. Levinson, H. Akbari, P. Berdahl, Measuring solarreflectance—Part II: review of practical methods, LBNL 2010), In someinstances, the backsheets exhibit a TSR value ranging from Rg;0=0.0 toRg;0,=1.0, such as Rg;0,=0.25 to Rg;0,=0.99, including Rg;0,=0.40 toRg;0,=0.98, e.g., as measured using the protocol referenced above.

In some instances, the coatings that include the carbonate materials arehighly reflective of near infra-red (NIR) light, ranging in someinstances from 10 to 99%, such as 50 to 99%. By NIR light is meant lighthaving a wavelength ranging from 700 nanometers (nm) to 2.5 mm. NIRreflectance may be determined using any convenient protocol, such asASTM C1371-04a(2010)el Standard Test Method for Determination ofEmittance of Materials Near Room Temperature Using Portable Emissometers(http://www.astm.org/Standards/C1371.htm) or ASTM G173-03(2012) StandardTables for Reference Solar Spectral Irradiances: Direct Normal andHemispherical on 37° Tilted Surface(http://rredc.nrel.gov/solar/spectra/am1.5/ASTMG173/ASTMG173.html). Insome instances, the coatings exhibit a NIR reflectance value rangingfrom Rg;0=0.0 to Rg;0=1.0, such as Rg;0=0.25 to Rg;0=0.99, includingRg;0=0.40 to Rg;0=0.98, e.g., as measured using the protocol referencedabove.

In some instances, the carbonate coatings are highly reflective ofultra-violet (UV) light, ranging in some instances from 10 to 99%, suchas 50 to 99%. By UV light is meant light having a wavelength rangingfrom 400 nm and 10 nm. UV reflectance may be determined using anyconvenient protocol, such as ASTM G173-03(2012) Standard Tables forReference Solar Spectral Irradiances: Direct Normal and Hemispherical on37° Tilted Surface. In some instances, the materials exhibit a UV valueranging from Rg;0=0.0 to Rg;0=1.0, such as Rg;0=0.25 to Rg;0=0.99,including Rg;0=0.4 to Rg;0=0.98, e.g., as measured using the protocolreferenced above.

In some instances, the coatings are reflective of visible light, e.g.,where reflectivity of visible light may vary, ranging in some instancesfrom 10 to 99%, such as 10 to 90%. By visible light is meant lighthaving a wavelength ranging from 380 nm to 740 nm. Visible lightreflectance properties may be determined using any convenient protocol,such as ASTM G173-03(2012) Standard Tables for Reference Solar SpectralIrradiances: Direct Normal and Hemispherical on 37° Tilted Surface. Insome instances, the coatings exhibit a visible light reflectance valueranging from Rg;0=0.0 to Rg;0=1.0, such as Rg;0=0.25 to Rg;0=0.99,including Rg;0=0.4 to Rg;0=0.98, e.g., as measured using the protocolreferenced above.

The materials making up the carbonate components are, in some instances,amorphous or microcrystalline, Where the materials are microcrystalline,the crystal size, e.g., as determined using the Scherrer equationapplied to the FWHM of X-ray diffraction pattern, is small, and in someinstances is 1000 microns or less in diameter, such as 100 microns orless in diameter, and including 10 microns or less in diameter. In someinstances, the crystal size ranges in diameter from 1000 μm to 0,001 μm,such as 10 to 0.001 μm, including 1 to 0.001 μm. In some instances, thecrystal size is chosen in view of the wavelength(s) of light that are tobe reflected. For example, where light in the visible spectrum is to bereflected, the crystal size range of the materials may be selected to beless than one-half the “to be reflected” range, so as to give rise tophotonic band gap. For example, where the to be reflected wavelengthrange of light is 100 to 1000 nm, the crystal size of the material maybe selected to be 50 nm or less, such as ranging from 1 to 50 nm, e.g.,5 to 25 nm. In some embodiments, the materials produced by methods ofthe invention may include rod-shaped crystals and amorphous solids. Therod-shaped crystals may vary in structure, and in certain embodimentshave length to diameter ratio ranging from 500 to 1, such as 10 to 1. Incertain embodiments, the length of the crystals ranges from 0.5 μm to500 μm, such as from 5 μm to 100 μm. In yet other embodiments,substantially completely amorphous solids are produced.

The density, porosity, and permeability of the coating materials mayvary according to the application. With respect to density, while thedensity of the material may vary, in some instances the density rangesfrom 5 g/cm³ to 0.01 g/cm³, such as 3 g/cm³ to 0.3 g/cm³and including2.7 g/cm³to 0.4 g/cm³. With respect to porosity, as determined by GasSurface Adsorption as determined by the BET method (Brown Emmett Teller(e.g., as described at http://en.wikipedia.org/wiki/BET_theory, S.Brunauer, P. H. Emmett and E. Teller, J. Am. Chem. Soc., 1938, 60, 309.doi:10.1021/ja01269a023) the porosity may range in some instances from100 m²/g to 0.1 m²/g, such as 60 m²/g to 1 m²/g and including 40 m²/g to1.5 m²/g. Wth respect to permeability, in some instances thepermeability of the material may range from 0.1 to 100 darcies, such as1 to 10 darcies, including 1 to 5 darcies (e.g., as determined using theprotocol described in H. Darcy, Les Fontaines Publiques de la Ville deDijon, Dalmont, Paris (1856)). Permeability may also be characterized byevaluating water absorption of the material. As determined by waterabsorption protocol, e.g., the water absorption of the material ranges,in some embodiments, from 0 to 25%, such as 1 to 15% and including from2 to 9%.

The hardness of the materials may also vary. In some instances, thematerials exhibit a Mohs hardness of 3 or greater, such as 5 or greater,including 6 or greater, where the hardness ranges in some instances from3 to 8, such as 4 to land including 5 to 6 Mohs (e.g., as determinedusing the protocol described in American Federation of MineralogicalSocieties. “Mohs Scale of Mineral Hardness”). Hardness may also berepresented in terms of tensile strength, e.g., as determined using theprotocol described in ASTM 01167. In some such instances, the materialmay exhibit a compressive strength of 100 to 3000 N, such as 400 to 2000N, including 500 to 1800 N.

In some embodiments, a the carbonate material includes one or morecontaminants predicted not to leach into the environment by one or moretests selected from the group consisting of Toxicity CharacteristicLeaching Procedure, Extraction Procedure Toxicity Test, SyntheticPrecipitation Leaching Procedure, California Waste Extraction Test,Soluble Threshold Limit Concentration, American Society for Testing andMaterials Extraction Test, and Multiple Extraction Procedure. Tests andcombinations of tests may be chosen depending upon likely contaminantsand storage conditions of the composition. For example, in someembodiments, the composition may include As, Cd, Cr, Hg, and Pb (orproducts thereof), each of which might be found in a waste gas stream ofa coal-fired power plant. Since TCLP tests for As, Ba, Cd, Cr, Pb, Hg,Se, and Ag, TCLP may be an appropriate test for aggregates describedherein.

In some embodiments, a carbonate composition of the invention includesAs, wherein the composition is predicted not to leach As into theenvironment. For example, a TCLP extract of the composition may provideless than 5.0 mg/L As indicating that the composition is not hazardouswith respect to As. In some embodiments, a carbonate composition of theinvention includes Cd, wherein the composition is predicted not to leachCd into the environment. For example, a TCLP extract of the compositionmay provide less than 1.0 mg/L Cd indicating that the composition is nothazardous with respect to Cd. In some embodiments, a carbonatecomposition of the invention includes Cr, wherein the composition ispredicted not to leach Cr into the environment. For example, a TCLPextract of the composition may provide less than 5.0 mg/L Cr indicatingthat the composition is not hazardous with respect to Cr. In someembodiments, a carbonate composition of the invention includes Hg,wherein the composition is predicted not to leach Hg into theenvironment. For example, a TCLP extract of the composition may provideless than 0.2 mg/L Hg indicating that the composition is not hazardouswith respect to Hg. In some embodiments, a carbonate composition of theinvention includes Pb, wherein the composition is predicted not to leachPb into the environment. For example, a TCLP extract of the compositionmay provide less than 5.0 mg/L Pb indicating that the composition is nothazardous with respect to Pb. In some embodiments, a carbonatecomposition and aggregate that includes of the same of the invention maybe non-hazardous with respect to a combination of different contaminantsin a given test. For example, the carbonate composition may benon-hazardous with respect to all metal contaminants in a given test. ATCLP extract of a composition, for instance, may be less than 5.0 mg/Lin As, 100.0 mg/L in Ba, 1.0 mg/L in Cd, 5.0 mg/mL in Cr, 5.0 mg/L inPb, 0.2 mg/L in Hg, 1.0 mg/L in Se, and 5.0 mg/L in Ag. Indeed, amajority if not all of the metals tested in a TCLP analysis on acomposition of the invention may be below detection limits. In someembodiments, a carbonate composition of the invention may benon-hazardous with respect to all (e.g., inorganic, organic, etc.)contaminants in a given test. In some embodiments, a carbonatecomposition of the invention may be non-hazardous with respect to allcontaminants in any combination of tests selected from the groupconsisting of Toxicity Characteristic Leaching Procedure, ExtractionProcedure Toxicity Test, Synthetic Precipitation Leaching Procedure,California Waste Extraction Test, Soluble Threshold Limit Concentration,American Society for Testing and Materials Extraction Test, and MultipleExtraction Procedure. As such, carbonate compositions and aggregatesincluding the same of the invention may effectively sequester CO₂ (e.g.,as carbonates, bicarbonates, or a combinations thereof) along withvarious chemical species (or co-products thereof) from waste gasstreams, industrial waste sources of divalent cations, industrial wastesources of proton-removing agents, or combinations thereof that might beconsidered contaminants if released into the environment. Compositionsof the invention incorporate environmental contaminants (e.g., metalsand co-products of metals such as Hg, Ag, As, Ba, Be, Cd, Co, Cr, Cu,Mn, Mo, Ni, Pb, Sb, Se, TI, V, Zn, or combinations thereof) in anon-leachable form.

The aggregate compositions of the invention include particles having acore region and a CO₂ sequestering carbonate coating on at least aportion of a surface of the core. The coating may cover 10% or more, 20%or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% ormore, 80% or more, 90% or more, including 95% or more of the surface ofthe core. The thickness of the carbonate layer may vary, as desired. Insome instances, the thickness may range from 0.1 μm to 10mm, such as 1μm to 1000 μm, including 10 μm to 500 μm.

The core of the coated particles of the aggregate compositions describedherein may vary widely. The core may be made up of any convenientaggregate material. Examples of suitable aggregate materials include,but are not limited to: natural mineral aggregate materials, e.g.,carbonate rocks, sand (e.g., natural silica sand), sandstone, gravel,granite, diorite, gabbro, basalt, etc.; and synthetic aggregatematerials, such as industrial byproduct aggregate materials, e.g.,blast-furnace slag, fly ash, municipal waste, and recycled concrete,etc. In some instances, the core comprises a material that is differentfrom the carbonate coating.

In some instances, the aggregates are lightweight aggregates. In suchinstances, the core of the coated particles of the aggregatecompositions described herein may vary widely, so long as when it iscoated it provides for the desired lightweight aggregate composition.The core may be made up of any convenient material. Examples of suitableaggregate materials include, but are not limited to: conventionallightweight aggregate materials, e.g., naturally occurring lightweightaggregate materials, such as crushed volcanic rocks, e.g., pumice,scoria or tuff, and synthetic materials, such as thermally treatedclays, shale, slate, diatomite, perlite, vermiculite, blast-furnace slagand fly ash; as well as unconventional porous materials, e.g., crushedcorals, synthetic materials like polymers and low density polymericmaterials, recycled wastes such as wood, fibrous materials, cement kilndust residual materials, recycled glass, various volcanic minerals,granite, silica bearing minerals, mine tailings and the like.

The physical properties of the coated particles of the aggregatecompositions may vary. Aggregates of the invention have a density thatmay vary so long as the aggregate provides the desired properties forthe use for which it will be employed, e.g., for the building materialin which it is employed. In certain instances, the density of theaggregate particles ranges from 1.1 to 5 gm/cc, such as 1.3 gm/cc to3.15 gm/cc, and including 1.8 gm/cc to 2.7 gm/cc. Other particledensities in embodiments of the invention, e.g., for lightweightaggregates, may range from 1.1 to 2.2 gm/cc, e.g., 1.2 to 2.0 g/cc or1.4 to 1.8 g/cc. In some embodiments the invention provides aggregatesthat range in bulk density (unit weight) from 50 lb/lb/ft³ to 200lb/ft³, or 75 lb/ft³ to 175 lb/ft³, or 50 lb/ft³ to 166 lb/ft³, or 75Ib/ft³ to 125 lb/ft³, or lb/ft³ to 115 lb/ft³, or 100 lb/ft³ to 266lb/ft³, or 125 lb/ft³ to lb/ft³, or 140 lb/ft³to 160 lb/ft³, or 50lb/ft³ to 200 lb/ft³. Some embodiments of the invention providelightweight aggregate, e.g., aggregate that has a bulk density (unitweight) of 75 lb/ft³ to 125 lb/ft³, such as 90 lb/ft³ to 115 lb/ft³. Insome instances, the lightweight aggregates have a weight ranging from 50to 1200 kg/m³, such as 80 to 11 kg/m³.

The hardness of the aggregate particles making up the aggregatecompositions of the invention may also vary, and in certain instancesthe hardness, expressed on the Mohs scale, ranges from 1.0 to 9, such as1 to 7, including 1 to 6 or 1 to 5. In some embodiments, the Mohr'shardness of aggregates of the invention ranges from 2-5, or 2-4. In someembodiments, the Mohs hardness ranges from 2-6. Other hardness scalesmay also be used to characterize the aggregate, such as the Rockwell,Vickers, or Brinell scales, and equivalent values to those of the Mohsscale may be used to characterize the aggregates of the invention; e.g.,a Vickers hardness rating of 250 corresponds to a Mohs rating of 3;conversions between the scales are known in the art.

The abrasion resistance of an aggregate may also be important, e.g., foruse in a roadway surface, where aggregates of high abrasion resistanceare useful to keep surfaces from polishing. Abrasion resistance isrelated to hardness but is not the same. Aggregates of the inventioninclude aggregates that have an abrasion resistance similar to that ofnatural limestone, or aggregates that have an abrasion resistancesuperior to natural limestone, as well as aggregates having an abrasionresistance lower than natural limestone, as measured by art acceptedmethods, such as ASTM C131-03. In some embodiments aggregates of theinvention have an abrasion resistance of less than 50%, or less than40%, or less than 35%, or less than 30%, or less than 25%, or less than20%, or less than 15%, or less than 10%, when measured by ASTM C131-03.

Aggregates of the invention may also have a porosity within a particularranges. As will be appreciated by those of skill in the art, in somecases a highly porous aggregate is desired, in others an aggregate ofmoderate porosity is desired, while in other cases aggregates of lowporosity, or no porosity, are desired. Porosities of aggregates of someembodiments of the invention, as measured by water uptake after ovendrying followed by full immersion for 60 minutes, expressed as % dryweight, can be in the range of 1-40%, such as 2-20%, or 2-15%, including2-10% or even 3-9%.

The dimensions of the aggregate particles may vary. Aggregatecompositions of the invention are particulate compositions that may insome embodiments be classified as fine or coarse. Fine aggregatesaccording to embodiments of the invention are particulate compositionsthat almost entirely pass through a Number 4 sieve (ASTM C 125 and ASTMC 33), Fine aggregate compositions according to embodiments of theinvention have an average particle size ranging from 10 μm to 4.75mm,such as 50 μm to 3.0 mm and including 75 μm to 2.0 mm. Coarse aggregatesof the invention are compositions that are predominantly retained on aNumber 4 sieve (ASTM C 125 and ASTM C 33). Coarse aggregate compositionsaccording to embodiments of the invention are compositions that have anaverage particle size ranging from 4.75 mm to 200 mm, such as 4.75 to150 mm in and including 5 to 100 mm. As used herein, “aggregate” mayalso in some embodiments encompass larger sizes, such as 3 in to 12 inor even 3 in to 24 in, or larger, such as 12 in to 48 in, or larger than48 in.

Concrete Dry Composites

Also provided are concrete dry composites that, upon combination with asuitable setting liquid (such as described below), produce a settablecomposition that sets and hardens into a concrete or a mortar. Concretedry composites as described herein include an amount of an aggregate,e.g., as described above, and a cement, such as a hydraulic cement. Theterm “hydraulic cement” is employed in its conventional sense to referto a composition which sets and hardens after combining with water or asolution where the solvent is water, e.g., an admixture solution.Setting and hardening of the product produced by combination of theconcrete dry composites of the invention with an aqueous liquid resultsfrom the production of hydrates that are formed from the cement uponreaction with water, where the hydrates are essentially insoluble inwater.

Aggregates of the invention find use in place of conventional naturalrock aggregates used in conventional concrete when combined with purePortland cement. Other hydraulic cements of interest in certainembodiments are Portland cement blends. The phrase “Portland cementblend” includes a hydraulic cement composition that includes a Portlandcement component and significant amount of a non-Portland cementcomponent. As the cements of the invention are Portland cement blends,the cements include a Portland cement component. The Portland cementcomponent may be any convenient Portland cement. As is known in the art,Portland cements are powder compositions produced by grinding Portlandcement clinker (more than 90%), a limited amount of calcium sulfatewhich controls the set time, and up to 5% minor constituents (as allowedby various standards). When the exhaust gases used to provide carbondioxide for the reaction contain SOx, then sufficient sulphate may bepresent as calcium sulfate in the precipitated material, either as acement or aggregate to off set the need for additional calcium sulfate.As defined by the European Standard EN197.1, “Portland cement clinker isa hydraulic material which shall consist of at least two-thirds by massof calcium silicates (3CaO.SiO₂ and 2CaO.SiO₂), the remainder consistingof aluminium- and iron-containing clinker phases and other compounds.The ratio of Ca° to SiO₂ shall not be less than 2.0. The magnesiumcontent (MgO) shall not exceed 5.0% by mass.” The concern about MgO isthat later in the setting reaction, magnesium hydroxide, brucite, mayform, leading to the deformation and weakening and cracking of thecement. In the case of magnesium carbonate containing cements, brucitewill not form as it may with MgO. In certain embodiments, the Portlandcement constituent of the present invention is any Portland cement thatsatisfies the ASTM Standards and Specifications of C150 (Types of theAmerican Society for Testing of Materials (ASTM C50-StandardSpecification for Portland Cement). ASTM C150 covers eight types ofPortland cement, each possessing different properties, and usedspecifically for those properties.

Also of interest as hydraulic cements are carbonate containing hydrauliccements. Such carbonate containing hydraulic cements, methods for theirmanufacture and use are described in U.S. Pat. No. 7,735,274; thedisclosure of which applications are herein incorporated by reference.

In certain embodiments, the hydraulic cement may be a blend of two ormore different kinds of hydraulic cements, such as Portland cement and acarbonate containing hydraulic cement. In certain embodiments, theamount of a first cement, e.g., Portland cement in the blend ranges from10 to 90% (w/w), such as 30 to 70% (w/w) and including 40 to 60% (w/w),e.g., a blend of 80% OPC and 20% carbonate hydraulic cement.

In some instances, the concrete dry composite compositions, as well asconcretes produced therefrom, have a CarbonStar Rating (CSR) that isless than the CSR of the control composition that does not include anaggregate of the invention. The Carbon Star Rating (CSR) is a value thatcharacterizes the embodied carbon (in the form of CaCO₃) for anyproduct, in comparison to how carbon intensive production of the productitself is (i.e., in terms of the production CO₂). The CSR is a metricbased on the embodied mass of CO₂ in a unit of concrete. Of the threecomponents in concrete—water, cement and aggregate—cement is by far themost significant contributor to CO₂ emissions, roughly 1:1 by mass (1ton cement produces roughly 1 ton 002). So, if a cubic yard of concreteuses 600 lb cement, then its CSR is 600. A cubic yard of concreteaccording to embodiments of the present invention which include 600 lbcement and in which at least a portion of the aggregate is carbonatecoated aggregate, e.g., as described above, will have a CSR that is lessthan 600, e.g., where the CSR may be 550 or less, such as 500 or less,including 400 or less, e.g., 250 or less, such as 100 or less, where insome instances the CSR may be a negative value, e.g., −100 or less, suchas −500 or less including −1000 or less, where in some instances the CSRof a cubic yard of concrete having 600 lbs cement may range from 500 to−5000, such as −100 to −4000, including −500 to −3000. To determine theCSR of a given cubic yard of concrete that includes carbonate coatedaggregate of the invention, an initial value of CO₂ generated for theproduction of the cement component of the concrete cubic yard isdetermined. For example, where the yard includes 600 lbs of cement, theinitial value of 600 is assigned to the yard. Next, the amount ofcarbonate coating in the yard is determined. Since the molecular weightof carbonate is 100 a.u., and 44% of carbonate is CO₂, the amount ofcarbonate coating is present in the yard is then multiplied by .44 andthe resultant value subtracted from the initial value in order to obtainthe CSR for the yard. For example, where a given yard of concrete mix ismade up of 6001bs of cement, 300 lbs of water, 1429 lbs of fineaggregate and 1739 lbs of coarse aggregate, the weight of a yard ofconcrete is 4068 lbs and the CSR is 600. If 10% of the total mass ofaggregate in this mix is replaced by carbonate coating, e.g., asdescribed above, the amount of carbonate present in the revised yard ofconcrete is 317 lbs. Multiplying this value by .44 yields 139,5.Subtracting this number from 600 provides a CSR of 460.5.

Settable Compositions

Settable compositions of the invention, such as concretes and mortars,are produced by combining a hydraulic cement with an amount of aggregate(fine for mortar, e.g., sand; coarse with or without fine for concrete)and an aqueous liquid, e.g., water, either at the same time or bypre-combining the cement with aggregate, and then combining theresultant dry components with water. The choice of coarse aggregatematerial for concrete mixes using cement compositions of the inventionmay have a minimum size of about ⅜ inch and can vary in size from thatminimum up to one inch or larger, including in gradations between theselimits. Finely divided aggregate is smaller than ⅜ inch in size andagain may be graduated in much finer sizes down to 200-sieve size or so.Fine aggregates may be present in both mortars and concretes of theinvention. The weight ratio of cement to aggregate in the dry componentsof the cement may vary, and in certain embodiments ranges from 1:10 to4:10, such as 2:10 to 5:10 and including from 55:1000 to 70:100.

The liquid phase, e.g., aqueous fluid, with which the dry component iscombined to produce the settable composition, e.g., concrete, may vary,from pure water to water that includes one or more solutes, additives,co-solvents, etc, as desired. The ratio of dry component to liquid phasethat is combined in preparing the settable composition may vary, and incertain embodiments ranges from 2:10 to 7:10, such as 3:10 to 6:10 andincluding 4:10 to 6:10.

In certain embodiments, the cements may be employed with one or moreadmixtures. Admixtures are compositions added to concrete to provide itwith desirable characteristics that are not obtainable with basicconcrete mixtures or to modify properties of the concrete to make itmore readily useable or more suitable for a particular purpose or forcost reduction. As is known in the art, an admixture is any material orcomposition, other than the hydraulic cement, aggregate and water, thatis used as a component of the concrete or mortar to enhance somecharacteristic, or lower the cost, thereof. The amount of admixture thatis employed may vary depending on the nature of the admixture. Incertain embodiments the amounts of these components range from 1 to 50%w/w, such as 2 to 10% w/w.

Admixtures of interest include finely divided mineral admixtures such ascementitious materials; pozzolans; pozzolanic and cementitiousmaterials; and nominally inert materials, Pozzolans include diatomaceousearth, opaline cherts, clays, shales, fly ash, silica fume, volcanictuffs and pumicites are some of the known pozzolans. Certain groundgranulated blast-furnace slags and high calcium fly ashes possess bothpozzolanic and cementitious properties. Nominally inert materials canalso include finely divided raw quartz, dolomites, limestone, marble,granite, and others. Fly ash is defined in ASTM C618.

Other types of admixture of interest include plasticizers, accelerators,retarders, air-entrainers, foaming agents, water reducers, corrosioninhibitors, and pigments.

As such, admixtures of interest include, but are not limited to: setaccelerators, set retarders, air-entraining agents, defoamers,alkali-reactivity reducers, bonding admixtures, dispersants, coloringadmixtures, corrosion inhibitors, dampproofing admixtures, gas formers,permeability reducers, pumping aids, shrinkage compensation admixtures,fungicidal admixtures, germicidal admixtures, insecticidal admixtures,rheology modifying agents, finely divided mineral admixtures, pozzolans,aggregates, wetting agents, strength enhancing agents, water repellents,and any other concrete or mortar admixture or additive. Admixtures arewell-known in the art and any suitable admixture of the above type orany other desired type may be used; see, e.g., U.S. Pat. No. 7,735,274,incorporated herein by reference in its entirety.

In some instances, the settable composition is produced using an amountof a bicarbonate rich product (BRP) admixture, which may be liquid orsolid form, e.g., as described in U.S. patent application Ser. No.14/112,495 published as United States Published Application PublicationNo. 2014/0234946; the disclosure of which is herein incorporated byreference.

In certain embodiments, settable compositions of the invention include acement employed with fibers, e.g., where one desires fiber-reinforcedconcrete. Fibers can be made of zirconia containing materials, steel,carbon, fiberglass, or synthetic materials, e.g., polypropylene, nylon,polyethylene, polyester, rayon, high-strength aramid, (i.e. Kevlar®), ormixtures thereof.

The components of the settable composition can be combined using anyconvenient protocol. Each material may be mixed at the time of work, orpart of or all of the materials may be mixed in advance. Alternatively,some of the materials are mixed with water with or without admixtures,such as high-range water-reducing admixtures, and then the remainingmaterials may be mixed therewith. As a mixing apparatus, anyconventional apparatus can be used. For example, Hobart mixer, slantcylinder mixer, Omni Mixer, Henschel mixer, V-type mixer, and Nautamixer can be employed.

Following the combination of the components to produce a settablecomposition (e.g., concrete), the settable compositions are in someinstances initially flowable compositions, and then set after a givenperiod of time. The setting time may vary, and in certain embodimentsranges from 30 minutes to 48 hours, such as 30 minutes to 24 hours andincluding from 1 hour to 4 hours,

The strength of the set product may also vary. In certain embodiments,the strength of the set cement may range from 5 Mpa to 70 MPa, such as10 MPa to 50 MPa and including from 20 MPa to 40 MPa. In certainembodiments, set products produced from cements of the invention areextremely durable e.g., as determined using the test method described atASTM 01157.

Structures

Aspects of the invention further include structures produced from theaggregates and settable compositions of the invention. As such, furtherembodiments include manmade structures that contain the aggregates ofthe invention and methods of their manufacture. Thus in some embodimentsthe invention provides a manmade structure that includes one or moreaggregates as described herein. The manmade structure may be anystructure in which an aggregate may be used, such as a building, dam,levee, roadway or any other manmade structure that incorporates anaggregate or rock. In some embodiments, the invention provides a manmadestructure, e.g., a building, a dam, or a roadway, that includes anaggregate of the invention, where in some instances the aggregate maycontain CO₂ from a fossil fuel source, e.g., as described above. In someembodiments the invention provides a method of manufacturing astructure, comprising providing an aggregate of the invention.

Utility

The subject aggregate compositions and settable compositions thatinclude the same, find use in a variety of different applications, suchas in building or construction materials. Specific structures in whichthe aggregates and/or settable compositions of the invention find useinclude, but are not limited to: pavements, architectural structures,e.g., buildings, foundations, motorways/roads, overpasses, parkingstructures, brick/block walls and footings for gates, fences and poles.Mortars of the invention find use in binding construction blocks, e.g.,bricks, together and filling gaps between construction blocks. Mortarscan also be used to fix existing structure, e.g., to replace sectionswhere the original mortar has become compromised or eroded, among otheruses.

Aggregates as discussed above are further described in U.S. ProvisionalApplication Ser. Nos. 62/163,107 and 62/163,118; the disclosures ofwhich are herein incorporated by reference.

Methods of Making and Acidic Bybroduct Remediation

Aggregates as described herein are conveniently fabricated using thecontinuous protocols as described above. Specifically, aggregates asdescribed herein may be fabricated by using the aggregates as seedstructures in a carbonate deposition continuous process, such asdescribed above, where the deposited carbonate material may be a CO₂sequestering carbonate material or other carbonate material.

With respect to aggregate production, raw input aggregate may bepretreated as desired prior to its use as seed structure in a continuousprocess. In some embodiments, the pre-treatment of the aggregate inputmaterial is used to remediate an acidic byproduct liquid. As such,aspects of the invention include methods of remediating an acidicbyproduct liquid produced by processes for sequestering CO₂, i.e., CO₂sequestration processes (i.e., methods, protocols, etc.) that result inCO₂ sequestration.

By remediate is meant improve or treat in some way to make the byproductliquid more acceptable, e,g., for subsequent disposal in the environmentor further use in another process. In some instances remediationincludes increasing the pH of the acidic by product liquid. While themagnitude of pH increase may vary, in some instances the magnitude is1.0 pH scale units or greater, such s 2.0 pH scale units or greater,including 3.0 pH scale units or greater. While the pH of the remediatedliquid may vary, in some instances the pH of the remediated liquidranges from 3.0 to 8.0, such as 3.5 to 7.5, including 4.0 to 7.0.

The acidic byproduct liquid that is treated in embodiments of theinvention may vary widely. In some instances, the acidic byproductliquid has a pH that is 3.0 or less, such as 2.5 or less, including 2.0or less, where in some instances the pH of the acidic byproduct liquidranges from 0 to 2.5, such as 0.5 to 1.5. In some instances, the acidicbyproduct liquid includes HCl. The acidic byproduct liquid may be anacidic liquid produced by a variety of different CO₂ sequestrationprocesses.

In some instances, the acidic by product liquid is a liquid produced bya bicarbonate mediated CO₂ sequestration protocol. In such protocols, abicarbonate rich product containing liquid, e.g., an liquid condensedphase (LCP) containing liquid, is contacted with a source of divalentcations, e.g,, divalent alkali earth metal cations, under conditionssufficient to produce a solid product (e.g., carbonate product) and CO₂.Such protocols include, but are not limited to, those described in U.S.patent application Ser. No. 14/112,495; the disclosure of which isherein incorporated by reference.

In some instances, the acidic byproduct liquid is one that is producedby an alkali enrichment module or component of a bicarbonate mediatedCO₂ sequestration process. By alkali enrichment protocol is meant thatthe methods employ an alkali enrichment protocol at some point duringthe method, e.g., to produce a CO₂ capture liquid, to enhance thealkalinity of a CO₂ charged liquid, etc. The alkali enrichment protocolmay be employed once or two or more times during a given method, and atdifferent stages of a given method. For example, an alkali enrichmentprotocol may be performed before and/or after a CO₂ capture liquidproduction step, e.g., as described in greater detail below. By “alkalienrichment protocol” is meant a method or process of increasing thealkalinity of a liquid. The alkalinity increase of a given liquid may bemanifested in a variety of different ways. In some instances, increasingthe alkalinity of a liquid is manifested as an increase the pH of theliquid. For example, a liquid may be processed to remove hydrogen ionsfrom the liquid to increase the alkalinity of the liquid. In suchinstances, the pH of the liquid may be increased by a desirable value,such as 0.10 or more, 0.20 or more, 0.25 or more, 0.50 or more, 0.75 ormore, 1.0 or more, 2.0 or more, etc. In some instances, the magnitude ofthe increase in pH may vary, ranging in some instances from 0.1 to 10,such as 1 to 9, including 2.5 to 7.5, e.g,, 3 to 7. As such, methods mayincrease the alkalinity of an initial liquid to produce a product liquidhaving a desired pH, where in some instances the pH of the productliquid ranges from 5 to 14, such as 6 to 13, including 7 to 12, e.g., 8to 11, where the product liquid may be viewed as an enhanced alkalinityliquid. The increase in alkalinity of a liquid may also be manifested asan increase in the dissolved inorganic carbon (DIC) content of liquid.The DIC is the sum of the concentrations of inorganic carbon species ina solution, represented by the equation: DIC=[CO₂*]+[HCO₃ ⁻]+[CO₃ ²⁻],where [CO₂*] is the sum of carbon dioxide ([CO₂]) and carbonic acid([H₂CO₃]) concentrations, [HCO₃ ⁻] is the bicarbonate concentration and[CO₃ ²⁻] is the carbonate concentration in the solution. The DIC of thealkali enriched liquid may vary, and in some instances may be 500 ppm orgreater, such as 5,000 ppm or greater, including 15,000 ppm or greater.In some instances, the DIC of the alkali enriched liquid may range from500 to 20,000 ppm, such as 7,500 to 15,000 ppm, including 8,000 to12,000 ppm. In some instances, alkali enrichment is manifested as anincrease in the concentration of bicarbonate species, e.g., NaHCO₃,e.g., to a concentration ranging from 5 to 500 mMolar, such as 10 to 200mMolar. In some instances, the alkali enrichment protocol is a membranemediated protocol, By membrane mediated protocol is meant a process ormethod which employs a membrane at some time during the method. As such,membrane mediated alkali enrichment protocols are those alkalienrichment processes in which a membrane is employed at some time duringthe process. While a given membrane mediated alkali enrichment protocolmay vary, in some instances the membrane mediated protocol includescontacting a first liquid, e.g., a feed liquid, and a second liquid,e.g., a draw liquid, to opposite sides of a membrane. Alkali enrichmentprotocols and systems for practicing the same that may be adapted foruse methods of the invention, e.g., as described above, include thosedescribed in U.S. patent application Ser. No. 14/636,043; the disclosureof which is herein incorporated by reference.

In addition to remediation of acidic byproduct liquids produced bybicarbonate mediated CO₂ sequestration process, aspects of the methodsalso include remediation of such liquids produced by carbonate mediatedCO₂ sequestering protocols, i.e., alkaline intensive protocols, in whicha CO₂ containing gas is contacted with an aqueous medium at pH of about10 or more. Examples of such protocols include, but are not limited to,those described in U.S. Pat. Nos. 8,333,944; 8,177,909; 8,137,455;8,114,214; 8,062,418; 8,006,446; 7,939,336; 7,931,809; 7,922,809;7,914,685; 7,906,028; 7,887,694; 7,829,053; 7,815,880; 7,771,684;7,753,618; 7,749,476; 7,744,761; and 7,735,274; the disclosures of whichare herein incorporated by reference.

Aspects of the invention include contacting the acidic byproduct liquidwith an acid neutralizing material under conditions sufficient toincrease the pH of the acidic byproduct liquid and thereby remediate theacidic byproduct liquid. In some instances, the acid neutralizingmaterial comprises a rock composition. Rock compositions of interest mayvary, where examples of rock compositions include, but are not limitedto: mafic rock, ultramafic rock, felsic rock, pumice rock, limestonerock, etc. In some instances, the rock neutralizing material is a finecomprising aggregate precursor composition. By fine comprises aggregateprecursor composition is meant a rock composition that includes rocks ofsuitable size for use as aggregate, e.g., in concretes, as well asfines. Fines that are removed may vary in sized, depending on theparticular application. In some instances, the fines that are moved arefines having a size smaller than that of coarse aggregate, which isdefined in the art as particles having a the grain size is above 4.75mm. In some instances, the fines that are removed are fines having asize that is smaller than fine aggregate, which is defined as aggregatepassing the 3/8″ (9.5-mm) sieve and almost entirely passing the No.4(4.75-mm) sieve and predominantly retained on the No. 200(75-micrometer) sieve. In some instances, the fines that are moved arefins that pass through a No. 200 sieve.

Contact of the acidic byproduct liquid and neutralizing material, e.g.,fine comprises aggregate precursor, may be accomplished using anyconvenient protocol. For examples, the liquid and material may bebrought together in a suitable chamber, e.g., reactor, and subjected toagitation as desired to provide for complete contact of the material andthe liquid.

Following contact, a remediated acidic byproduct liquid, i.e., productliquid, is produced, such as described above. In addition, where theneutralizing material is a fine comprising aggregate, a productaggregate is produced in which the amount of undesirable fine particlesis reduced. While the magnitude of fine particle reduction in theaggregate precursor may vary, in some instances the magnitude is suchthat wt. % of the fine particles in the precursor is 2-fold or greater,such as 5-fold or greater, including 10-fold or greater, relative to theamount that is present in the product aggregate. In some instances theproduct aggregate includes substantially no fines, e.g., 5 wt. % or lessfines, such as 3 wt. % or less fines, including 1 wt. % or less fines.It is noted that while the above embodiment of treating a finecomprising aggregate precursor composition to remove fines is describedin terms of employing an acidic byproduct liquid, the invention is notso limited. As such, aspects of the invention include methods oftreating a fine comprising aggregate composition to reduce the amount offines present therein and produce a product aggregate using any suitableacidic liquid, which liquid may in some instances have a pH of 6 orless, e.g., 5 or less, 4 or less, 3 or less, 2 or less, including 1 orless.

FIG. 2 provides a schematic representation of a specific embodiment of amethod in accordance with an embodiment of the invention. As shown inFIG. 2, flue gas is contacted with water in an AE capture module (e.g.,as described in PCT Application Serial No. PCT/US2015/018361 nowpublished as WO 2015/134408 (the disclosure of which is hereinincorporated by reference) to produce a bicarbonate rich product (i.e.,HCO³⁻ water), depleted flue gas and an acidic byproduct (i.e., acidicsalty water). The acidic salty water is contacted with a fine comprisingaggregate, which neutralizes the acidic salty water and produces aproduct aggregate which is substantially free of fines. The productaggregate is then combined with the bicarbonate rich product water in acoating and mineralization module, e.g., as described above, whichyields a carbonate coated aggregate (comprises CO₂ sequestered from theflue gas) and product CO₂, which is recycled to the flue gas and runthrough the capture module.

The following examples are offered by way of illustration and not by wayof limitation.

Experimental I. Laminar Flow Reactor A. EXAMPLE 1 1. Test Method

30 L of 0.15M NaHCO₃ were circulated through the laminar flow reactorshown in FIG. 3 at a rate of 6.5 L/min in a counter clock-wise fashion.A solution of CaCl₂ and MgCl₂ (a liquid divalent cation source) wasadded at a rate of 8 ml/min, ending at a 2:1 ratio of bicarbonate tooverall divalent cation. The reactor was run for 24 hours and thenturned off. The materials shown in the SEM images of FIG. 4 arematerials that were located just after the divalence injection. The SEMimages shown in FIG. 4 were taken using a Hitatchi TM-3030, mounting onan aluminum stub with carbon tape under 15 kV voltage.

The larger fraction of materials was measured on a Horiba LA-300 byadding deionized water to the LA-300 sample cup. Samples werecirculated, de-bubbled and tested without sonication. Beam was aligned,and blank test taken as background. Sample was mixed well andtransferred to the LA-300 by pipette. Samples were measured in 3consecutive measurements once % T and distribution stabilized. Theparticle size distribution of the product is shown in FIG. 5.

Mortar was mixed using the synthetic ooid like materials produced asdescribed above using common methods similar to ASTM 0109. The wet ooidswere used in the mix design, and the mix design was reduced in similarweights of sand and water, equivalent to the weight of the wet ooids.The results of functional assays of the result produce are shown in FIG.6.

2. Discussion

Carbonate materials produced by way of a normal precipitation procedureresult in slurries composed of residual moisture and small precipitates.These precipitates are normally on the size range of 0.01-15 μ. Largersand sized materials and loose precipitate were found on the bottom ofreactor after 24 hour circulation and slow dose divalent addition. Byrecirculating the laminar flow continuous reactor larger particlesbetween 30 μ and >200 μ were produced. When tested in accordance withASTM 0109 mortar testing in a fashion considering sand and wateradditions, the materials showed equivalent 7 day performance andincreased early strength (See FIG. 6).

B. EXAMPLE 2 1. Test Method:

45L of 0.18M NaHCO₃ and 0.05M Na₂SO₄ (a bicarbonate containing liquid)were circulated through the laminar flow reactor shown in FIG. 1 at arate of 6.5 L/min in a counter clock-wise fashion. A solution of CaCl₂and MgCl₇ (a liquid divalent cation source) was added at a rate of 16ml/min, ending at a 2:1 ratio of bicarbonate to overall divalence. Thereactor was run for 24 hours and then turned off. The materials shown inthe SEM images of FIG. 7 are materials that were located just after thedivalence injection. SEM images were taken using a Hitatchi TM-3030,mounting on an aluminum stub with carbon tape under 15 kV voltage.

FTIR spectra were recorded using a Nicolet IS-10 by Thermo-Fisher with aHeNe laser and a fast recovery deuterated triglycerine sulfate (DIGS)detector. Scans were collected on a Germanium ATR crystal at resolutionof 16 and at optical velocity of 0.4747.

2. Discussion/Conclusion:

FTIR of the hard and soft scale showed a notable differences. FTIRanalysis of the hard scale showed characteristic variation at the 1450and 1119 cm-1 bond vibrations. 1450 cm-1 relates to the v3 asymmetric0-0 bond vibration and 1119 cm-1 relates to the v1 symmetric C—O bondvibration. SEM images at equivalent magnification exhibit a differencebetween non aggregated/soft precipitate and the microstructure of thehard scale. The hard scale contains a continuous phase of carbonateadhering common precipitate particles. X-ray Diffraction resultsindicated that the hard scale was predominantly calcite (74%) with acomplimenting amount of aragonite (20%) and the remainder being sodiumchloride residual. While the soft scale crystallographic analysisresulted in magnesian calcite (76%) and the remaining balance beingaragonite.

Continuous Beaker Reactor A. Materials and Methods:

Chemistries described in table 1 below were dosed into the beaker of thereactor shown in FIG. 8 at variable rates between 6.1 and 121.1 LPD.

TABLE 1 Continuous Flow Beaker Reactor Objective Result Chemisty 1Literature Case/Base Case N.A. 0.035M NaHCO3, 0.17M CaCl2, 1.03M NaCl 2Increased Saturation Seated in tube 0.15M NaHCO3, 0.075M CaCl2 3 50 C.,HCO3{circumflex over ( )}2 - Diurnal Diurnal cycle - scaled tube 0.15MNaHCO3, 0.075M CaCl2 4 Stir, Heat Diurnal, Complex Heating element scale0.3M NaHCO3, 0.05M Na2SO4, 0.075M CaCl2, 0.075M Chem. MgCl2*6H2O, 0.005MSrCl2 5 Addition of Nitorgen purge Heating element scale & N2 0.3MNaHCO3, 0.05M Na2SO4, 0.075M CaCl2, 0.075M MgCl2*6H2O, 0.005M SrCl2 6Complex chemistry (Ca, Mg, Sr) Heating element scale & N2 0.3M NaHCO3,0.05M Na2SO4, 0.075M CaCl2, 0.075M Diurnal MgCl2*6H2O, 0.005M SrCl2 7Calcite Chem. Templating 0.6M NaHCO3, 0.3M CaCl2 8 Templating (overflow)Hard Scale (Overflow zone) & stirbar 0.18M NaHCO3, 0.05M Na2SO4, 0.13MCaCl2, 0.05M MgCl2 (anyh) 9 Templating Scaling on BP cements &aggregates & 0.18M NaHCO3, 0.05M Na2SO4, 0.13M CaCl2, 0.05M StirbarMgCl2 (anyh)

As shown in FIG. 8, a vacuum pump removed liquids from the top of thecontinuous beaker reactor into a decanting vessel. Experiments includedvariation of temperature (22-40C), introduction of nitrogen (1 scfm),stir speed (400 rpm), rates of dosing (100-1000 L/min), saturation indexvariation as well as varied chemistries.

B. Discussion/Conclusion:

Two types of scale were seen in these results: a hard scale and a softeragglomerated material. The hard scale exhibited the same v3, v1 FTIRpeak as seen highlighted in Reactor 1 experiments. SEM of materialsshowed various scales. Those that were termed ‘hard scales’ showedsimilar microstructure to the examples in Reactor 1 experiments.Pictures of various produced materials are provided in FIGS. 9 to 11.

III. Percolation Pressure Drop A. Materials and Methods:

Chemistries as detailed in Table 2 were dosed into the dP reactorillustrated in FIG. 12.

Pressure Drop (dP) Continuous Reactor Objective Result Chemistry 1 BaseCase Lithification on Fritt 0.18M NaHCO3, 0.05M Na2SO4, 0.13M CaCl2,0.05M MgCl2 (anyh) 2 Template Pack Localized Lithification 0.18M NaHCO3,0.05M Na2SO4, 0.13M CaCl2, 0.05M MgCl2 (anyh) 3 BR-LCP Lithification ofFritt 0.273M NaHCO3, 0.13M CaCl2, 0.05M MgCl2

Flow rates varied between 3 L/min to 100 ml/min of alkaline flow and theflow rate of the divalent chemical reagent ranged between 111 ml/min to2 ml/min. Solutions were passed through a series of pressure regulatorsdecreasing the pressure from ˜150 psi by ˜50 psi at each of 3 pressuredrop stages. The three regulators associated to pressure drops were eachbacked by an air-liquid separator.

B. Discussion/Conclusion:

Two types of materials were also seen from this test, hard liquifiedscaled carbonate as well as precipitated carbonate formed mostly in theliquids capture bucket. See FIG. 13. FTIR analysis and SEM analysis wasin agreement with results seen previously in the laminar flow reactorand the continuous beaker reactor.

IV. Fluidized Bed Reactor: A. Materials and Methods:

Various materials were also template and aggressively coated using afluidized bed type reactor. The materials were inserted into a fluidizedbed reactor as seen in FIG. 14. The materials were exposed to liquidfeeds between 1-5 L/min of an alkaline feed stream as well as a cationcontaining feed stream. The zone of accretion was in the fluidized bed.Materials were exposed to both calcium and magnesium containing feedwaters. Various experiments are seen below with relevant yields.

Fluid Bed Reactor Name Reactor Template Catonic Feed Pump & Flow RateAnionic Feed Final Weight Precipitate Run #1 MR1 S na 85MHP40 L-1 Run #2MR1 S 400 g 250 mM CaCl2 85MHP40 L-1 500 mM NaHCO3 310 g (na) Run #3 MR1S 400 g 500 mM CaCl2 85MHP40 L-1 1M NaHCO3 320 g (na) Run #4 MR1 XL 2 kg500 mM CaCl2 85MHP40 L-1 1M NaHCO3 2740 g wet Run #5 MR1 XL 2 kgs 250 mMCaCl2 85MHP40 L-5 500 mM NaHCO3 1940 g dry Run #6 MR1 S 400 g - Ooids 71mM CaCl2 + 85MHP40 L-1 500 mM NaHCO3 440 g dry 178 mM MgCl2 Run #7 MR1 S400 g - Limestone 500 mM CaCl2 85MHP40 L-1 1M NaHCO3 640 g dry Run #8MR1 S 400 g - Silica Sand 500 mM CaCl2 85MHP40 L-1 1M NaHCO3 680 g-dryRun #9 MR1 1500 g - Limestone 500 mM CaCl2 85MHP40 L-1.5 1M NaHCO3 2890g-wet Run #10 MR1 1500 g - Silica Sand 500 mM CaCl2 85MHP40 L-1.5 1MNaHCO3 2850 g-wet Run #11 MR1 1500 g - Limestone 500 mM CaCl2 85MHP40L-1.5 1M NaHCO3 Run #12 MR1 1500 g - Silica Sand 500 mM CaCl2 85MHP40L-1.5 1M NaHCO3 Run #13 MR1 1500 g - Ooids 500 mM CaCl2 85MHP40 L-1.5 1MNaHCO3 Run #14 MR1 1500 g - Ooids 500 mM CaCl2 85MHP40 L-1.5 1M NaHCO3Run #15 MR1 XL 2000 g - Ooids 100 mM CaCl2 Tetra 185 200 mM NaHCO3 2140g-dry 130 g GPD - 1LPM Run #16 MR1 XL 2000 g - Ooids 50 mM CaCl2 Tetra185 100 mM NaHCO3 2050 g-dry 100 g GPD - 1LPM

B. Discussion/Conclusion:

The coated materials can be seen in FIG. 15 (SEM). Specifically shownare coated silica sand and limestone sand materials, as well as thecross section of these materials. The materials have increased albedoand show high reflectance when placed on a roofing shingle. Solarreflectance between 38% and 69%% is shown in FIG. 16. Accreted sandmaterials have been tested with ASTM C109 like procedures yielding thedata seen in FIG. 17. The materials exhibit similar performance tonon-accreted samples.

V. Aggregate Production A. CO₂ Sequestering Aggregate

1 kg of normal weight sand was exposed to 15 L each of calcium chlorideand bicarbonate rich liquid condensed phase containing solution. Duringthis reaction materials were fluidized in a circulating reactor in acontinuous reaction process. FIG. 18A provides a picture of the pumiceprior to coating, while FIG. 18B provides a picture of the pumice aftercoating.

B. Lightweight Aggregate

15.3 kg of pumice from Northern California was exposed to 363 L each of:0.25M calcium chloride and ˜0.5M bicarbonate rich liquid condensed phasecontaining solution. Materials were agitated periodically at a rate of 1rph. Solutions were introduced at varying rates between 200-600 ml/minby way of centrifugal pump. FIG. 19A provides a picture of the pumiceprior to coating, while FIG. 19B provides a picture of the pumice aftercoating.

The coated pumice lightweight aggregate was further used in thefollowing concrete mix:

-   Cement-24.1 lb-   Vulcan Sand-40.7 lb (dry)-   Lava Rock-11.25 lb (dry)-   Water-11.3 lb

The resultant mix exhibited the following properties in accordance withASTM 0330, shown in Table 1, below.

TABLE 1 ASTM C330 specific characteristics. LWCA Density AbsorptionAbrasion Pumice (C19) 37 pcf 15.8% 8.1% Production Lot (C18) 39 pcf14.1%  9%

The associated Carbon Star Rating for this mix design that includedlight weight coarse aggregate was 515.

VI. Aggregate Mediated Acid Remediation

2 g (pumice) and 10 g (limestone) samples of rock (see left hand side ofFIG. 20, top and bottom) were exposed to 100 mL 0.01N HCl and thefollowing acid remediation resulted (further data available whenneeded):

pH pH Rxn. Rate Rxn. Rate equilibrium equilibrium 1st Order 2nd OrderRock Mineral Conductivity (mass (mass Rate Rate (source) (FTIR) Mass (i)Mass (f) (mS/cm) limited) unlimited) [H+]/min. [H+]/min. PumiceAmorphous  2 g 1.4 g 1.26 4 7.9 8.47E−04 2.65E−06 (Lake Silica CountyCA) Limestone Calcite 10 g 9.0 g 1.4 7.7 8.1 5.48E−03 2.74E−10 (CEMEXBrooksville FL)

As can be seen, the product aggregate shown top and bottom on the righthand side of FIG. 20 is substantially free of all fines, demonstratedthat contact with the 100 mL 0.01N HCl effectively removed substantiallyall fines from the aggregate 1.0 precursor to produce a productaggregate. Other types of rocks that may be employed in such methodsinclude, but are not limited to: Talc, Serpentine, Forsterite,Vermiculite and Phlogopite, and other Mafic and Ultramafic rocks.

VII. Improving Solar Reflectance of Colored Roofing Granules by CaCO₃Coating

A method has been developed to produce a high reflective roofingmaterial with color, without having to use high reflective pigments.Increase of solar reflectance has been observed with CaCO₃ coating ondark granules as well as light-colored granules. Due to the hightransmittance characteristics of CaCO₃, the color of the originalgranule is retained below 200 μm of coating. Solar reflectance, however,is increased due to high reflectance property of CaCO₃.

A. Materials and Methods

CaCO₃ precipitates were coated on raw substrate granules using singlechemistry, or by combining multiple chemistry of the following mineralsyntheses:

Calcite: 0.33M CaCl₂+0.667M NaHCO₃

Vaterite: 0.13M CaCl₂+0.05M MgCl₂+0.18M NaHCO₃+0.05M Na₂SO₄

Amorphous carbonate: 0.15M CaCl₂+0.6M MgCl₂+0.75M NaHCO₃ Similarly sizedgranules (Santa Cruz marble, Blue Mountain limestone, or dark rhyolite)were washed and placed in the trough reactor as shown in FIG. 21 and thereactants were inserted at 19-39 ml/min using peristaltic pumps. Thesolutions percolated through the granules for 5 hours and coated thesurfaces of the granules. The powdered precipitates which didn't getcoated on granules were collected separately. The coated granules weredried and sieved.

B. Results

CaCO₃ is reflective and has a potential for its uses in roofinggranules. In addition to high reflectance property, CaCO₃ has hightransmittance compared to TiO₂, therefore lower opacity and lower hidingpower. Due to such high transmittance of CaCO₃, a thin coating willincrease the solar reflectance of the granule but keep the dark color ofthe granule. It has been found from our experiment that 200 μm ofcoating is required to completely hide the original granule color.Therefore, CaCO₃ coating under 200 μm can retain the original color andyet enhance reflectivity of the coating.

With CaCO₃ coatings on Santa Cruz marble, Bluemoutain limestone, anddark rhyolite, the solar reflectance has increased 0.15-0.28 from theoriginal granule's reflectance. The increase of solar reflectancedepended on the thickness of the coating. The color of the granulebecame lighter with thicker CaCO₃ coatings, while the color stayed closeto the original granule with thinner coatings.

Notwithstanding the appended clauses, the disclosure is also defined bythe following clauses:

-   1. A method of producing a solid CO₂ sequestering carbonate    material, the method comprising:

introducing a divalent cation source into a flowing aqueous bicarbonateand/or carbonate containing liquid under conditions sufficient such thata non-slurry solid phase CO₂ sequestering carbonate material is producedin the flowing aqueous bicarbonate and/or carbonate containing liquid.

-   2. The method according to Clause 1, wherein the liquid is a    bicarbonate containing liquid.-   3. The method according to Clause 2, wherein the bicarbonate    containing liquid is a liquid produced from a CO₂ containing gas.-   4. The method according to Clause 3, wherein the CO₂ containing gas    is a multi-component gaseous stream.-   5. The method according to Clause 4, wherein the multi-component    gaseous stream is a flue gas.-   6. The method according to any of Clauses 1 to 5, wherein the    non-slurry solid phase CO₂ sequestering carbonate material is    freshwater stable.-   7. The method according to any of Clauses 1 to 6, wherein the    non-slurry solid phase CO₂ sequestering carbonate material is a    particulate composition.-   8. The method according to Clause 7, wherein the particulate    composition has a mean particle diameter of 30 microns or greater.-   9. The method according to any of the preceding clauses, wherein the    method comprises producing the solid phase CO₂ sequestering    carbonate material in association with a seed structure.-   10. The method according to Clause 9, wherein the solid phase CO₂    sequestering carbonate material is produced on at least one of a    surface of or in a depression of the seed structure.-   11. The method according to Clause 10 where the seed structure in a    porous and permeable aggregate material that is in-filled by the    solid phase sequestering carbonate material to produce a less    porous, denser solid aggregate.-   12. The method according to Clause 11, where the in-filled aggregate    is in-filled on the outer margin to a larger extent than in the    inner portion, making the new aggregate less dense in the inner    region as compared to the outer margin, to produce a light weight    aggregate.-   13. The method according to any of Clauses 9 to 12, wherein the seed    structure comprises a carbonate material.-   14. The method according to any of Clauses 9 to 12, wherein the seed    structure comprises a non-carbonate material.-   15. The method according to any of Clauses 9 to 14, wherein the seed    structure is submerged in the flowing liquid.-   16. The method according to any of Clauses 9 to 14, wherein the seed    structure is not submerged in the flowing liquid and the liquid is    flowed over a surface of the seed structure.-   17. The method according to any of the preceding clauses, wherein    the method is carried out in a continuous reactor.-   18. The method according to any of the preceding clauses, wherein    the solid phase CO₂ sequestering carbonate material is produced in a    fluidized bed subunit of the continuous reactor.-   19. The method according to any of the preceding clauses, wherein    the method further comprises separating the non-slurry solid phase    CO₂ sequestering carbonate material from the liquid.-   20. The method according to any of the preceding clauses, wherein    the method further comprises producing the bicarbonate containing    liquid.-   21. The method according to Clause 20, wherein the bicarbonate    containing liquid is produced by contacting a CO₂ containing gas    with an aqueous medium.-   22. The method according to any of the preceding clauses, wherein    the method further comprises producing a building material from the    non-slurry solid phase CO₂ sequestering carbonate material.-   23. The method according to Clause 22, wherein the building material    comprises an aggregate.-   24. The method according to Clause 22, wherein the building material    comprises roofing granules.-   25. A continuous reactor configured to produce a solid CO₂    sequestering carbonate material, the reactor comprising: a flowing    aqueous bicarbonate containing liquid; a divalent cation introducer    configured to introduce divalent cations at an introduction location    into the flowing aqueous bicarbonate liquid; and a non-slurry solid    phase CO₂ sequestering carbonate material production location.-   26. The continuous reactor according to Clause 25, wherein the    reactor comprises a flow modulator.-   27. The continuous reactor according to Clauses 25 or 26, wherein    the reactor comprises a pressure modulator.-   28. The continuous reactor according to any of Clauses 25 to 27,    wherein the reactor comprises a temperature modulator.-   29. The continuous reactor according to any of Clauses 25 to 28,    wherein the non-slurry solid phase CO₂ sequestering carbonate    material production location comprises seed structures.-   30. The continuous reactor according to Clause 29, wherein the seed    structures comprise granules.-   31. The continuous reactor according to any of Clauses 29 or 30,    wherein the seed structures comprise a carbonate material.-   32. The continuous reactor according to any of Clauses 29 or 30,    wherein the seed structures comprise a non-carbonate material.-   33. The continuous reactor according to any of Clauses 29 to 32,    wherein the reactor is configured to submerge the seed structures in    the liquid.-   34. The continuous reactor according to any of Clauses 29 to 32,    wherein the reactor is not configured to submerge the seed    structures in the liquid.-   35. The continuous reactor according to any of Clauses 25 to 34,    wherein the non-slurry solid phase CO₂ sequestering carbonate    material production location comprises a fluidized bed.-   36. The continuous reactor according to any of Clauses 25 to 35,    wherein the continuous reactor is fluidically coupled to an aqueous    bicarbonate containing liquid production unit.-   37. The continuous reactor according to any of Clauses 25 to 36,    wherein the continuous reactor is operatively coupled to a building    material production unit.-   38. The continuous reactor according to Clause 37, wherein the    building material comprises an aggregate.-   39. The continuous reactor according to Clause 37, wherein the    building material comprises roofing granules.

Notwithstanding the appended clauses, the disclosure is also defined bythe following clauses:

-   1. An aggregate composition comprising aggregate particles    comprising a core and a CO₂ sequestering carbonate coating on at    least a portion of a surface of the core.-   2. The aggregate composition according to Clause 1, wherein the    carbonate coating is present on at least substantially all surfaces    of the core.-   3. The aggregate composition according to Clauses 1 or 2, wherein    the carbonate coating is present on all surfaces of the core.-   4. The aggregate composition according to any of the preceding    clauses, wherein the carbonate coating has a thickness ranging from    0.1 μm to 10 mm.-   5. The aggregate composition according to any of the preceding    clauses, wherein the carbonate coating comprises a    microcrystalline/amorphous carbonate material.-   6. The aggregate composition according to Clause 5, wherein the    microcrystalline/amorphous carbonate component has a crystal size    ranging from 0 or X-ray Amorphous to 100 μm.-   7. The aggregate composition according to Clauses 5 or 6, wherein    the microcrystalline/amorphous carbonate component comprises at    least one of calcium carbonate and magnesium carbonate.-   8. The aggregate composition according to any of the preceding    clauses, wherein the core comprises a material that is different    from the carbonate coating.-   9. The aggregate composition according to any of the preceding    clauses, wherein the aggregate particles comprise fine aggregate    particles.-   10. The aggregate composition according to any of the preceding    clauses, wherein the aggregate particles comprise coarse aggregate    particles.-   11. The aggregate composition according to any of the preceding    clauses, wherein the carbonate coating comprises at least one of    calcium and magnesium.-   12. The aggregate composition according to Clause 11, wherein the    carbonate coating comprises at least one of As, Cd, Cr, Hg, and Pb.-   13. The aggregate composition according to any of the preceding    clauses, wherein the carbonate coating comprises at least one    non-carbonate compound selected from hydroxides, silicates,    sulfates, sulfites, phosphates and arsenates.-   14. A concrete dry composite comprising:

(a) a cement; and (b) an aggregate composition according to any ofClauses 1 to 13.

-   15. The concrete dry composite according to Clause 14, wherein the    cement comprises a hydraulic cement.-   16. The concrete dry composite according to Clause 15, wherein the    hydraulic cement comprises a Portland cement.-   17. A settable composition produced by combining an aggregate    according to any of Clauses 1 to 10, a cement and a liquid.-   18. The settable composition according to Clause 17, wherein the    cement is a hydraulic cement.-   19. The settable composition according to Clause 18, wherein the    hydraulic cement comprises a Portland cement.-   20. The settable composition according to any of Clauses 17 to 19,    further comprising a supplementary cementitious material.-   21. The settable composition according to any of Clauses 17 to 20,    further comprising an admixture.-   22. The settable composition according to any of Clauses 17 to 21,    wherein the settable composition is flowable.-   23. A solid formed structure produced from a settable composition    according to any of Clauses 17 to 22.-   24. A method comprising combining an aggregate according to any of    Clauses 1 to 13, a cement and a liquid in a manner sufficient to    produce a settable composition that sets into a solid product.-   25. The method according to Clause 24, wherein the liquid comprises    an aqueous liquid.

Notwithstanding the appended clauses, the disclosure is also defined bythe following clauses:

-   1. A lightweight aggregate composition comprising lightweight    aggregate particles comprising a porous aggregate core and a    carbonate coating on at least a portion of a surface of the porous    aggregate core.-   2. The lightweight aggregate composition according to Clause 1,    wherein the carbonate coating is present on at least substantially    all surfaces of the porous aggregate core.-   3. The lightweight aggregate composition according to Clauses 1 or    2, wherein the carbonate coating is present on all surfaces of the    porous aggregate core.-   4. The lightweight aggregate composition according to any of the    preceding clauses, wherein the carbonate coating has a thickness    ranging from 0.1 μm to 10 mm.-   5. The lightweight aggregate composition according to any of the    preceding clauses, wherein the carbonate coating comprises a    microcrystalline/amorphous carbonate material.-   6. The lightweight aggregate composition according to Clause 5,    wherein the microcrystalline/amorphous carbonate component has a    crystal size ranging from 0 or X-ray Amorphous to 100 μm.-   7. The lightweight aggregate composition according to Clauses 5 or    6, wherein the microcrystalline/amorphous carbonate component    comprises at least one of calcium carbonate and magnesium carbonate.-   8. The lightweight aggregate composition according to any of the    preceding clauses, wherein the carbonate coating comprises a CO₂    sequestering material.-   9. The lightweight aggregate composition according to any of the    preceding clauses, wherein the porous aggregate core comprises a    material that is different from the carbonate coating.-   10. The lightweight aggregate composition according to any of the    preceding clauses, wherein the porous aggregate core comprises    expanded clay, expanded shale, expanded slate, expanded blast    furnace slag, expanded vermiculite, expanded perlite or pumice.-   11. The lightweight aggregate composition according to any of the    preceding clauses, wherein the lightweight aggregate particles    comprise fine aggregate particles.-   12. The lightweight aggregate composition according to any of the    preceding clauses, wherein the lightweight aggregate particles    comprise coarse aggregate particles.-   13. The lightweight aggregate composition according to any of the    preceding clauses, wherein the carbonate coating comprises at least    one of calcium and magnesium.-   14. The lightweight aggregate composition according to Clause 13,    wherein the carbonate coating comprises at least one of As, Cd, Cr,    Hg, and Pb.-   15. The lightweight aggregate composition according to any of the    preceding clauses, wherein the carbonate coating comprises at least    one non-carbonate compound selected from hydroxides, silicates,    sulfates, sulfites, phosphates and arsenates.-   16. A concrete dry composite comprising:

(a) a cement; and (b)a lightweight aggregate composition according toany of Clauses 1 to 15.

-   17. The concrete dry composite according to Clause 16, wherein the    cement comprises a hydraulic cement.-   18. The concrete dry composite according to Clause 17, wherein the    hydraulic cement comprises a Portland cement.-   19. A settable composition produced by combining a lightweight    aggregate according to any of Clauses 1 to 15, a cement and a    liquid.-   20. The settable composition according to Clause 19, wherein the    cement is a hydraulic cement.-   21. The settable composition according to Clause 20, wherein the    hydraulic cement comprises a Portland cement.-   22. The settable composition according to any of Clauses 19 to 21,    further comprising a supplementary cementitious material.-   23. The settable composition according to any of Clauses 19 to 22,    further comprising an admixture.-   24. The settable composition according to any of Clauses 19 to 23,    wherein the settable composition is flowable.-   25. A solid formed structure produced from a settable composition    according to any of Clauses 19 to 24.-   26. A method comprising combining an aggregate according to any of    Clauses 1 to 15, a cement and a liquid in a manner sufficient to    produce a settable composition that sets into a solid product.-   27. The method according to Clause 26, wherein the liquid comprises    an aqueous liquid.

Notwithstanding the appended clauses, the disclosure is also defined bythe following clauses:

-   1. A method of increasing the pH of a CO₂ sequestration process    generated acidic byproduct liquid, the method comprising:

contacting the acidic byproduct liquid with an acid neutralizingmaterial under conditions sufficient to increase the pH of the acidicbyproduct liquid.

-   2. The method according to Clause 1, wherein the magnitude of    increase in pH is 1 or greater.-   3. The method according to Clause 2, wherein the magnitude of    increase in pH ranges from 1.0 to 7.0.-   4. The method according any of Clauses 1 to 3, wherein the acid    neutralizing material comprises a fine comprising aggregate    precursor and contact occurs under conditions sufficient to remove    fines from the aggregate precursor to produce a product aggregate.-   5. The method according to Clause 4, wherein wt. % of fines in the    aggregate precursor is 2 fold or greater than in the product    aggregate.-   6. The method according to Clause 5, wherein method results in    removal of substantially all of the fines from the precursor    aggregate such that the product aggregate comprises substantially no    fines.-   7. The method according to Clause 6, wherein the amount of fines in    the product aggregate is 5 wt. % or less.-   8. The method according to any of the preceding clauses, wherein the    acidic byproduct liquid is produced by a bicarbonate mediated CO₂    sequestration process.-   9. The method according to Clause 8, wherein acidic byproduct liquid    is produced by an alkali enrichment protocol of the bicarbonate    mediated CO₂ sequestration process.-   10. The method according to any of Clauses 1 to 7, wherein the    acidic byproduct liquid is produced by a carbonate mediated CO₂    sequestration process.-   11. A method of remediating an acidic aqueous liquid byproduct of an    alkali enrichment protocol, the method comprising:

contacting an acidic aqueous liquid byproduct from an alkali enrichmentprotocol with an acid neutralizing material in a manner sufficient toincrease the pH of the acidic aqueous liquid byproduct to remediate theacidic aqueous liquid byproduct.

-   12. The method according to Clause 11, wherein the alkali enrichment    protocol comprises a membrane mediated alkali enrichment protocol.-   13. The method according to any of Clauses 11 to 12, wherein the    acid neutralizing material comprises a rock composition.-   14. The method according to Clause 13, wherein the rock composition    comprises mafic, ultramafic and/or felsic rock.-   15. The method according to Clause 13, wherein the rock composition    comprises a pumice or limestone.-   16. The method according to any of Clauses 11 to 15, wherein the pH    of the acidic aqueous liquid byproduct is increased to a value    ranging from 3.0 to 8.0.-   17. The method according to any of Clauses 11 to 16, wherein the    alkali enrichment protocol is part of a CO₂ sequestration protocol.-   18. A method for sequestering CO₂ from a gaseous source of CO₂, the    method comprising:

a) subjecting an initial liquid to an alkali enrichment protocol toproduce an enhanced alkalinity liquid and an acidic aqueous liquidbyproduct; and

b) employing the enhanced alkalinity liquid in a CO₂ sequestrationprotocol to sequester CO₂ and contacting the acidic aqueous liquidbyproduct with an acid neutralizing material in a manner sufficient toincrease the pH of the acidic aqueous liquid byproduct to remediate theacidic aqueous liquid byproduct.

-   19. The method according to Clause 18, wherein the alkali enrichment    protocol is a membrane mediated protocol.-   20. The method according to any of Clauses 18 and 19, wherein the    method comprises producing the initial liquid by contacting a source    liquid with the gaseous source of CO₂.-   21. The method according to any of Clauses 18 to 20, wherein the    method comprises contacting the enhanced alkalinity liquid with the    gaseous source of CO₂ under conditions sufficient to produce an LCP    containing liquid.-   22. The method according to any of Clauses 18 to 21, wherein the    gaseous source of CO₂ is a gaseous stream of pure CO₂.-   23. The method according to any of Clauses 18 to 22, wherein the    gaseous source of CO₂ is a multi-component gaseous stream.-   24. The method according to Clause 23, wherein the gaseous source of    CO₂ is a flue gas.-   25. The method according to Clause 24, wherein the flue gas is    obtained from an industrial source.-   26. The method according to any of Clauses 18 to 25, wherein the pH    of the acidic aqueous liquid byproduct is increased to a value    ranging from 3.0 to 8.0.-   27. The method according to any of Clauses 18 to 26, wherein the    method comprises recycling the remediated acidic aqueous liquid    byproduct to the alkali enrichment protocol.-   28. The method according to any of Clauses 18 to 27, wherein the    acid neutralizing material comprises a rock composition.-   29. The method according to Clause 28, wherein the rock composition    comprises mafic, ultramafic and/or felsic rock.-   30. The method according to any of Clauses 28 to 29, wherein the    rock composition comprises a pumice.-   31. The method according to any of Clauses 18 to 30, wherein the CO₂    sequestration protocol comprises producing a carbonate from a LCP    that comprises dissolved inorganic carbon (DIC) obtained from the    gaseous source of CO₂.

32. The method according to Clause 31, wherein the carbonate is producedby introducing a divalent cation source into an LCP containing liquidunder conditions sufficient to produce the carbonate.

-   33. The method according to Clause 32, wherein the divalent cation    source is introduced into a flowing LCP containing liquid under    conditions sufficient such that a non-slurry solid phase CO₂    sequestering carbonate material is produced in the flowing LCP    containing liquid.-   34. The method according to Clause 33, wherein the method comprises    producing the solid phase CO₂ sequestering carbonate material in    association with a seed composition.-   35. The method according to Clause 34, wherein the seed composition    comprises a rock composition that has been contacted with the acidic    aqueous liquid byproduct.-   36. The method according to any of Clauses 28 to 35, wherein the    method produces an aggregate.-   37. The method according to any of Clauses 18 to 36, wherein the    method produces pure CO₂ gas.-   38. A method of reducing the fine particle component of a mined rock    composition, the method comprising:

contacting the mined rock composition with an acidic aqueous liquidbyproduct from an alkali enrichment protocol in a manner sufficient toreduce the fine particle component of the mined rock composition.

-   39. The method according to Clause 38, wherein the fine particle    component of the mined rock composition is decreased by 10 wt% or    greater.-   40. The method according to any of Clauses 38 to 39, wherein the    method is a method of producing an aggregate.-   41. A system comprising:

an input for a CO₂ sequestration process generated acidic byproductliquid;

an input for an acid neutralizing material; and

a reactor for contacting a CO₂ sequestration process generated acidicbyproduct liquid and an acid neutralizing material in a mannersufficient to produce a product liquid having a pH that is increasedrelative to the acidic byproduct liquid; and

an output for the product liquid.

-   42. The system according to Clause 41, wherein the acidic byproduct    liquid is produced by a bicarbonate mediated CO₂ sequestration    process.-   43. The system according to Clause 42, wherein acidic byproduct    liquid is produced by an alkali enrichment protocol of the    bicarbonate mediated CO₂ sequestration process.-   44. The system according to any of Clauses 41 to 43, wherein the    neutralizing material comprises a rock.-   45. The system according to Clause 44, wherein the rock comprises an    fine comprises aggregate precursor.-   46. The system according to Clause 45, wherein the system comprises    an output for a product aggregate.-   47. The system according to any of the preceding clauses, wherein    the system further comprises an alkali enrichment module operatively    coupled to the input for a CO₂ sequestration process generated    acidic byproduct liquid.-   48. The system according to any of the preceding clauses, wherein    the system further comprises a carbonate production module.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it is readily apparent to those of ordinary skill in theart in light of the teachings of this invention that certain changes andmodifications may be made thereto without departing from the spirit orscope of the appended claims.

Accordingly, the preceding merely illustrates the principles of theinvention. It will be appreciated that those skilled in the art will beable to devise various arrangements which, although not explicitlydescribed or shown herein, embody the principles of the invention andare included within its spirit and scope. Furthermore, all examples andconditional language recited herein are principally intended to aid thereader in understanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the presentinvention, therefore, is not intended to be limited to the exemplaryembodiments shown and described herein. Rather, the scope and spirit ofpresent invention is embodied by the appended claims.

1-24. (canceled)
 25. A continuous reactor configured to produce a solidCO₂ sequestering carbonate material, the reactor comprising: a flowingaqueous bicarbonate containing liquid; a divalent cation introducerconfigured to introduce divalent cations at an introduction locationinto the flowing aqueous bicarbonate liquid; and a non-slurry solidphase CO₂ sequestering carbonate material production location.
 26. Thecontinuous reactor according to claim 25, wherein the reactor comprisesa flow modulator.
 27. The continuous reactor according to claim 25,wherein the reactor comprises a pressure modulator.
 28. The continuousreactor according to claim 25, wherein the reactor comprises atemperature modulator.
 29. The continuous reactor according to claim 25,wherein the non-slurry solid phase CO₂ sequestering carbonate materialproduction location comprises seed structures.
 30. The continuousreactor according to claim 29, wherein the seed structures comprisegranules.
 31. The continuous reactor according to claim 29, wherein theseed structures comprise a carbonate material.
 32. The continuousreactor according to claim 29, wherein the seed structures comprise anon-carbonate material.
 33. The continuous reactor according to claim29, wherein the reactor is configured to submerge the seed structures inthe liquid.
 34. The continuous reactor according to claim 29, whereinthe reactor is not configured to submerge the seed structures in theliquid.
 35. The continuous reactor according to claim 25, wherein thenon-slurry solid phase CO₂ sequestering carbonate material productionlocation comprises a fluidized bed.
 36. The continuous reactor accordingto claim 25, wherein the continuous reactor is fluidically coupled to anaqueous bicarbonate containing liquid production unit.
 37. Thecontinuous reactor according to claim 25any of claims 25 to 36, whereinthe continuous reactor is operatively coupled to a building materialproduction unit.
 38. The continuous reactor according to claim 37,wherein the building material comprises an aggregate.
 39. The continuousreactor according to claim 37, wherein the building material comprisesroofing granules.